diff --git a/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/EditorHeader.tsx b/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/EditorHeader.tsx
index 76b6da54ed..4f19b249b9 100644
--- a/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/EditorHeader.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/EditorHeader.tsx
@@ -127,12 +127,16 @@ export default function Editor({
   }, [currentModal])
 
   useEffect(() => {
-    if (!templateString) return
+    if (!templateString) {
+      return
+    }
     const parsedTemplates = JSON.parse(templateString)
     const filteredTemplate = parsedTemplates.filter(
       (template: Template) => template.language === language
     )
-    if (filteredTemplate.length === 0) return
+    if (filteredTemplate.length === 0) {
+      return
+    }
     setTemplateCode(filteredTemplate[0].code[0].text)
   }, [language])
 
@@ -200,7 +204,9 @@ export default function Editor({
       if (res.status === 401) {
         showSignIn()
         toast.error('Log in first to submit your code')
-      } else toast.error('Please try again later.')
+      } else {
+        toast.error('Please try again later.')
+      }
     }
   }
 
@@ -223,16 +229,22 @@ export default function Editor({
       localStorage.setItem(storageKey.current, templateCode)
       setCode(templateCode)
       toast.success('Successfully reset the code')
-    } else toast.error('Failed to reset the code')
+    } else {
+      toast.error('Failed to reset the code')
+    }
   }
 
   const checkSaved = () => {
     const code = getCode()
     if (storageKey.current !== undefined) {
       const storedCode = getCodeFromLocalStorage(storageKey.current)
-      if (storedCode && storedCode === code) return true
-      else if (!storedCode && templateCode === code) return true
-      else return false
+      if (storedCode && storedCode === code) {
+        return true
+      } else if (!storedCode && templateCode === code) {
+        return true
+      } else {
+        return false
+      }
     }
     return true
   }
diff --git a/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/RunTestButton.tsx b/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/RunTestButton.tsx
index a5c3cf61f8..b6f806d174 100644
--- a/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/RunTestButton.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/_components/EditorHeader/RunTestButton.tsx
@@ -93,7 +93,7 @@ export default function RunTestButton({
     }
   })
 
-  const submitTest = async () => {
+  const submitTest = () => {
     const code = getCode()
     const testcases = getUserTestcases()
 
diff --git a/apps/frontend/app/(client)/(code-editor)/_components/EditorResizablePanel.tsx b/apps/frontend/app/(client)/(code-editor)/_components/EditorResizablePanel.tsx
index 3a3b0344ee..96fa607aeb 100644
--- a/apps/frontend/app/(client)/(code-editor)/_components/EditorResizablePanel.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/_components/EditorResizablePanel.tsx
@@ -9,7 +9,7 @@ import {
 import { ScrollArea, ScrollBar } from '@/components/shadcn/scroll-area'
 import { Tabs, TabsList, TabsTrigger } from '@/components/shadcn/tabs'
 import { useLanguageStore, useCodeStore } from '@/stores/editor'
-import type { Language, ProblemDetail } from '@/types/type'
+import type { ProblemDetail } from '@/types/type'
 import type { Route } from 'next'
 import Link from 'next/link'
 import { usePathname } from 'next/navigation'
@@ -154,7 +154,7 @@ function CodeEditorInEditorResizablePanel({
   return (
     <CodeEditor
       value={code ?? ''}
-      language={language as Language}
+      language={language}
       onChange={setCode}
       enableCopyPaste={enableCopyPaste}
       height="100%"
diff --git a/apps/frontend/app/(client)/(code-editor)/_components/TestcasePanel/TestcasePanel.tsx b/apps/frontend/app/(client)/(code-editor)/_components/TestcasePanel/TestcasePanel.tsx
index b0e32452ca..a14c84e4c0 100644
--- a/apps/frontend/app/(client)/(code-editor)/_components/TestcasePanel/TestcasePanel.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/_components/TestcasePanel/TestcasePanel.tsx
@@ -232,7 +232,9 @@ function TestSummary({
 }
 
 function TestResultDetail({ data }: { data: TestResultDetail | undefined }) {
-  if (data === undefined) return null
+  if (data === undefined) {
+    return null
+  }
 
   return (
     <div className="px-8 pt-5">
diff --git a/apps/frontend/app/(client)/(code-editor)/_components/WhitespaceVisualizer.tsx b/apps/frontend/app/(client)/(code-editor)/_components/WhitespaceVisualizer.tsx
index f2289b93e8..35b5b31229 100644
--- a/apps/frontend/app/(client)/(code-editor)/_components/WhitespaceVisualizer.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/_components/WhitespaceVisualizer.tsx
@@ -26,7 +26,7 @@ export function WhitespaceVisualizer({
   const visibleLines = lines.slice(0, 3).join('\n')
   const truncatedText =
     lines.length > 3
-      ? visibleLines + '\n<span style="color: rgb(150, 150, 150);">...</span>'
+      ? `${visibleLines}\n<span style="color: rgb(150, 150, 150);">...</span>`
       : visibleLines
 
   return (
diff --git a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/finished/problem/[problemId]/_components/ContestEditorSkeleton.tsx b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/finished/problem/[problemId]/_components/ContestEditorSkeleton.tsx
index 348b61e0a1..7206a4ecae 100644
--- a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/finished/problem/[problemId]/_components/ContestEditorSkeleton.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/finished/problem/[problemId]/_components/ContestEditorSkeleton.tsx
@@ -35,11 +35,8 @@ export default function ContestEditorSkeleton() {
             <button
               type="button"
               className="hidden items-center gap-2 rounded-md border-0 px-4 py-1 md:flex"
-            ></button>
-            <button
-              type="button"
-              className="flex gap-2 px-4 py-1 md:hidden"
-            ></button>
+            />
+            <button type="button" className="flex gap-2 px-4 py-1 md:hidden" />
           </div>
         </div>
       </header>
@@ -76,7 +73,7 @@ export default function ContestEditorSkeleton() {
             </div>
           </div>
         </div>
-        <div className="relative w-px bg-slate-500" role="separator"></div>
+        <div className="relative w-px bg-slate-500" role="separator" />
         <div className="w-2/3 bg-[#222939]">
           <div className="flex h-12 items-center justify-end border-b border-slate-700 bg-[#222939] px-6">
             <button className="h-8 w-[77px] rounded-md bg-slate-600 text-red-500">
@@ -94,7 +91,7 @@ export default function ContestEditorSkeleton() {
             <button className="h-8 w-10 rounded-md bg-slate-600">C</button>
           </div>
           <div className="h-full bg-[#121728] p-4">
-            <pre className="h-96 overflow-auto rounded-md bg-[#222939] p-4 font-mono text-sm text-gray-300"></pre>
+            <pre className="h-96 overflow-auto rounded-md bg-[#222939] p-4 font-mono text-sm text-gray-300" />
           </div>
         </div>
       </div>
diff --git a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/layout.tsx b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/layout.tsx
index 8377f880dc..84d40332e0 100644
--- a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/layout.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/layout.tsx
@@ -1,6 +1,6 @@
 import EditorLayout from '@/app/(client)/(code-editor)/_components/EditorLayout'
 
-export default async function layout({
+export default function layout({
   params,
   children
 }: {
diff --git a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/[submissionId]/page.tsx b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/[submissionId]/page.tsx
index 41de08b3f7..9433400ac3 100644
--- a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/[submissionId]/page.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/[submissionId]/page.tsx
@@ -4,7 +4,7 @@ import Link from 'next/link'
 import { Suspense } from 'react'
 import SubmissionDetail from '../_components/SubmissionDetail'
 
-export default async function Page({
+export default function Page({
   params
 }: {
   params: {
diff --git a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/_components/SubmissionDetail.tsx b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/_components/SubmissionDetail.tsx
index 78121bba16..f11af3c0c4 100644
--- a/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/_components/SubmissionDetail.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/contest/[contestId]/problem/[problemId]/submission/_components/SubmissionDetail.tsx
@@ -34,7 +34,7 @@ export default async function SubmissionDetail({
 
   const submission: SubmissionDetail = res.ok ? await res.json() : dataIfError
 
-  if (submission.result == 'Judging') {
+  if (submission.result === 'Judging') {
     revalidateTag(`submission/${submissionId}`)
   }
 
@@ -107,9 +107,7 @@ export default async function SubmissionDetail({
           </Table>
         </div>
       )}
-      {res.ok ? (
-        <></>
-      ) : (
+      {res.ok ? null : (
         <div className="absolute left-0 top-0 z-10 flex h-full w-full flex-col items-center justify-center gap-1 backdrop-blur">
           <IoIosLock size={100} />
           <p className="mt-4 text-xl font-semibold">Access Denied</p>
diff --git a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/layout.tsx b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/layout.tsx
index f26f701614..bccdb3ac48 100644
--- a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/layout.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/layout.tsx
@@ -1,6 +1,6 @@
 import EditorLayout from '@/app/(client)/(code-editor)/_components/EditorLayout'
 
-export default async function layout({
+export default function layout({
   params,
   children
 }: {
diff --git a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/[submissionId]/page.tsx b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/[submissionId]/page.tsx
index 70320beb64..44716bc753 100644
--- a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/[submissionId]/page.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/[submissionId]/page.tsx
@@ -4,7 +4,7 @@ import Link from 'next/link'
 import { Suspense } from 'react'
 import SubmissionDetail from '../_components/SubmissionDetail'
 
-export default async function Page({
+export default function Page({
   params
 }: {
   params: {
diff --git a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/_components/SubmissionDetail.tsx b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/_components/SubmissionDetail.tsx
index a270edbc70..801b39d32c 100644
--- a/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/_components/SubmissionDetail.tsx
+++ b/apps/frontend/app/(client)/(code-editor)/problem/[problemId]/submission/_components/SubmissionDetail.tsx
@@ -31,7 +31,7 @@ export default async function SubmissionDetail({
 
   const submission: SubmissionDetail = res.ok ? await res.json() : dataIfError
 
-  if (submission.result == 'Judging') {
+  if (submission.result === 'Judging') {
     revalidateTag(`submission/${submissionId}`)
   }
 
@@ -98,9 +98,7 @@ export default async function SubmissionDetail({
           </Table>
         </div>
       )}
-      {res.ok ? (
-        <></>
-      ) : (
+      {res.ok ? null : (
         <div className="absolute left-0 top-0 z-10 flex h-full w-full flex-col items-center justify-center gap-1 backdrop-blur">
           <p className="mt-4 font-mono text-xl font-semibold">Access Denied</p>
           <p className="w-10/12 text-center">
diff --git a/apps/frontend/app/(client)/(main)/_components/SearchBar.tsx b/apps/frontend/app/(client)/(main)/_components/SearchBar.tsx
index 959686c5c4..1b889f04cf 100644
--- a/apps/frontend/app/(client)/(main)/_components/SearchBar.tsx
+++ b/apps/frontend/app/(client)/(main)/_components/SearchBar.tsx
@@ -29,10 +29,12 @@ export default function SearchBar({ className }: SearchBarProps) {
     // set search data to newParam
     if (data.search) {
       newParam.set('search', data.search)
-    } else newParam.delete('search')
+    } else {
+      newParam.delete('search')
+    }
     const newParamString = newParam.toString()
     router.push(
-      `${pathname}${newParamString ? '?' + newParamString : ''}` as Route,
+      `${pathname}${newParamString ? `?${newParamString}` : ''}` as Route,
       {
         scroll: false
       }
diff --git a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/_components/RegisterButton.tsx b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/_components/RegisterButton.tsx
index c4b511da2e..f9631e117c 100644
--- a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/_components/RegisterButton.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/_components/RegisterButton.tsx
@@ -70,7 +70,7 @@ export default function RegisterButton({
     resolver: zodResolver(schema)
   })
 
-  const onSubmit = async () => {
+  const onSubmit = () => {
     clickRegister(id)
   }
 
diff --git a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/page.tsx b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/page.tsx
index 9f1181e29f..cccbbf424b 100644
--- a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/page.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/page.tsx
@@ -34,12 +34,17 @@ export default async function ContestTop({ params }: ContestTopProps) {
   const startTime = new Date(data.startTime)
   const endTime = new Date(data.endTime)
   const currentTime = new Date()
-  const state =
-    currentTime >= endTime
-      ? 'Finished'
-      : currentTime < startTime
-        ? 'Upcoming'
-        : 'Ongoing'
+  const state = (() => {
+    if (currentTime >= endTime) {
+      return 'Finished'
+    }
+
+    if (currentTime < startTime) {
+      return 'Upcoming'
+    }
+
+    return 'Ongoing'
+  })()
 
   return (
     <>
diff --git a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/Columns.tsx b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/Columns.tsx
index 73c9c3bc23..583b2ea33c 100644
--- a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/Columns.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/Columns.tsx
@@ -51,10 +51,8 @@ export const columns: ColumnDef<ContestProblem>[] = [
     header: () => 'Score',
     accessorKey: 'score',
     cell: ({ row }) =>
-      row.original.maxScore != null ? (
-        `${row.original.score ?? '-'} / ${row.original.maxScore}`
-      ) : (
-        <></>
-      )
+      row.original.maxScore !== null
+        ? `${row.original.score ?? '-'} / ${row.original.maxScore}`
+        : null
   }
 ]
diff --git a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/SubmissionDetailContent.tsx b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/SubmissionDetailContent.tsx
index 8e853cde6f..2600d3f6f0 100644
--- a/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/SubmissionDetailContent.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/[contestId]/@tabs/problem/_components/SubmissionDetailContent.tsx
@@ -13,7 +13,7 @@ import {
   TableRow
 } from '@/components/shadcn/table'
 import { dateFormatter, getResultColor } from '@/libs/utils'
-import type { ContestProblem, Language } from '@/types/type'
+import type { ContestProblem } from '@/types/type'
 import { useSuspenseQuery } from '@tanstack/react-query'
 
 interface SubmissionDetailProps {
@@ -109,11 +109,7 @@ export function SubmissionDetailContent({
                       </TableCell>
                       <TableCell>{item.cpuTime} ms</TableCell>
                       <TableCell>
-                        {(
-                          (item?.memoryUsage as number) /
-                          (1024 * 1024)
-                        ).toFixed(2)}{' '}
-                        MB
+                        {(item?.memoryUsage / (1024 * 1024)).toFixed(2)} MB
                       </TableCell>
                     </TableRow>
                   ))}
@@ -125,7 +121,7 @@ export function SubmissionDetailContent({
           <h2 className="mb-3 font-bold">Source Code</h2>
           <CodeEditor
             value={submission?.code}
-            language={submission?.language as Language}
+            language={submission?.language}
             readOnly
             className="max-h-96 min-h-16 w-full"
           />
diff --git a/apps/frontend/app/(client)/(main)/contest/_components/ContestCardList.tsx b/apps/frontend/app/(client)/(main)/contest/_components/ContestCardList.tsx
index 7dd495f80d..895f03a40f 100644
--- a/apps/frontend/app/(client)/(main)/contest/_components/ContestCardList.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/_components/ContestCardList.tsx
@@ -66,9 +66,13 @@ function ContestCardCarousel({
   const chunks = []
 
   if (itemsPerSlide === 3) {
-    for (let i = 0; i < data.length; i += 3) chunks.push(data.slice(i, i + 3))
+    for (let i = 0; i < data.length; i += 3) {
+      chunks.push(data.slice(i, i + 3))
+    }
   } else if (itemsPerSlide === 2) {
-    for (let i = 0; i < data.length; i += 2) chunks.push(data.slice(i, i + 2))
+    for (let i = 0; i < data.length; i += 2) {
+      chunks.push(data.slice(i, i + 2))
+    }
   }
 
   return (
@@ -117,15 +121,15 @@ export default async function Contest({
     session ? await getRegisteredContests() : await getContests()
   ).filter(
     (contest) =>
-      contest.status.toLowerCase() === 'registered' + type.toLowerCase() ||
+      contest.status.toLowerCase() === `registered${type.toLowerCase()}` ||
       contest.status.toLowerCase() === type.toLowerCase()
   )
 
-  data.sort((a, b) => +new Date(a.startTime) - +new Date(b.startTime))
+  data.sort(
+    (a, b) => new Date(a.startTime).getTime() - new Date(b.startTime).getTime()
+  )
 
-  return data.length === 0 ? (
-    <></>
-  ) : (
+  return data.length === 0 ? null : (
     <>
       <ContestCardCarousel itemsPerSlide={3} title={title} data={data} />
       <ContestCardCarousel itemsPerSlide={2} title={title} data={data} />
diff --git a/apps/frontend/app/(client)/(main)/contest/_components/ContestTabs.tsx b/apps/frontend/app/(client)/(main)/contest/_components/ContestTabs.tsx
index 4bb141743c..66ca15f6de 100644
--- a/apps/frontend/app/(client)/(main)/contest/_components/ContestTabs.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/_components/ContestTabs.tsx
@@ -10,7 +10,9 @@ export default function ContestTabs({ contestId }: { contestId: string }) {
   const pathname = usePathname()
 
   const isCurrentTab = (tab: string) => {
-    if (tab === '') return pathname === `/contest/${id}`
+    if (tab === '') {
+      return pathname === `/contest/${id}`
+    }
     return pathname.startsWith(`/contest/${id}/${tab}`)
   }
 
diff --git a/apps/frontend/app/(client)/(main)/contest/_components/FinishedTableColumns.tsx b/apps/frontend/app/(client)/(main)/contest/_components/FinishedTableColumns.tsx
index 2383f38076..f65c384baa 100644
--- a/apps/frontend/app/(client)/(main)/contest/_components/FinishedTableColumns.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/_components/FinishedTableColumns.tsx
@@ -35,8 +35,9 @@ export const columns: ColumnDef<Contest>[] = [
     header: 'Period',
     accessorKey: 'period',
     cell: ({ row }) =>
-      dateFormatter(row.original.startTime, 'YYYY-MM-DD') +
-      ' ~ ' +
-      dateFormatter(row.original.endTime, 'YYYY-MM-DD')
+      `${dateFormatter(row.original.startTime, 'YYYY-MM-DD')} ~ ${dateFormatter(
+        row.original.endTime,
+        'YYYY-MM-DD'
+      )}`
   }
 ]
diff --git a/apps/frontend/app/(client)/(main)/contest/_components/RegisteredContestTable.tsx b/apps/frontend/app/(client)/(main)/contest/_components/RegisteredContestTable.tsx
index 2871330784..5fce4f958d 100644
--- a/apps/frontend/app/(client)/(main)/contest/_components/RegisteredContestTable.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/_components/RegisteredContestTable.tsx
@@ -53,18 +53,16 @@ export default async function RegisteredContestTable({
   const data = await getFinishedContests(search)
 
   return (
-    <>
-      <DataTable
-        data={data}
-        columns={columns}
-        headerStyle={{
-          title: 'text-left w-2/5 md:w-1/2',
-          status: 'w-1/5 md:w-1/6',
-          participants: 'w-1/5 md:w-1/6',
-          period: 'w-1/5 md:w-1/3'
-        }}
-        linked
-      />
-    </>
+    <DataTable
+      data={data}
+      columns={columns}
+      headerStyle={{
+        title: 'text-left w-2/5 md:w-1/2',
+        status: 'w-1/5 md:w-1/6',
+        participants: 'w-1/5 md:w-1/6',
+        period: 'w-1/5 md:w-1/3'
+      }}
+      linked
+    />
   )
 }
diff --git a/apps/frontend/app/(client)/(main)/contest/_components/RegisteredTableColumns.tsx b/apps/frontend/app/(client)/(main)/contest/_components/RegisteredTableColumns.tsx
index 6344353655..5428499659 100644
--- a/apps/frontend/app/(client)/(main)/contest/_components/RegisteredTableColumns.tsx
+++ b/apps/frontend/app/(client)/(main)/contest/_components/RegisteredTableColumns.tsx
@@ -29,8 +29,9 @@ export const columns: ColumnDef<Contest>[] = [
     header: 'Period',
     accessorKey: 'period',
     cell: ({ row }) =>
-      dateFormatter(row.original.startTime, 'YYYY-MM-DD') +
-      ' ~ ' +
-      dateFormatter(row.original.endTime, 'YYYY-MM-DD')
+      `${dateFormatter(row.original.startTime, 'YYYY-MM-DD')} ~ ${dateFormatter(
+        row.original.endTime,
+        'YYYY-MM-DD'
+      )}`
   }
 ]
diff --git a/apps/frontend/app/(client)/(main)/notice/[noticeId]/page.tsx b/apps/frontend/app/(client)/(main)/notice/[noticeId]/page.tsx
index a2f5aefa28..c871cb9c10 100644
--- a/apps/frontend/app/(client)/(main)/notice/[noticeId]/page.tsx
+++ b/apps/frontend/app/(client)/(main)/notice/[noticeId]/page.tsx
@@ -23,7 +23,7 @@ export default async function NoticeDetail({
     current: { title, content, createTime, createdBy },
     prev,
     next
-  } = await fetch(baseUrl + `/notice/${noticeId}`).then((res) => res.json())
+  } = await fetch(`${baseUrl}/notice/${noticeId}`).then((res) => res.json())
 
   return (
     <article>
diff --git a/apps/frontend/app/(client)/(main)/problem/_components/Columns.tsx b/apps/frontend/app/(client)/(main)/problem/_components/Columns.tsx
index 70e5aa2eb9..b550b94893 100644
--- a/apps/frontend/app/(client)/(main)/problem/_components/Columns.tsx
+++ b/apps/frontend/app/(client)/(main)/problem/_components/Columns.tsx
@@ -1,7 +1,7 @@
 'use client'
 
 import { Badge } from '@/components/shadcn/badge'
-import type { Level, Problem } from '@/types/type'
+import type { Problem } from '@/types/type'
 import type { ColumnDef } from '@tanstack/react-table'
 import SortButton from './SortButton'
 
@@ -19,7 +19,7 @@ export const columns: ColumnDef<Problem>[] = [
     header: () => <SortButton order="level">Level</SortButton>,
     accessorKey: 'difficulty',
     cell: ({ row }) => (
-      <Badge className="rounded-md" variant={row.original.difficulty as Level}>
+      <Badge className="rounded-md" variant={row.original.difficulty}>
         {row.original.difficulty}
       </Badge>
     )
diff --git a/apps/frontend/app/(client)/(main)/problem/_components/SortButton.tsx b/apps/frontend/app/(client)/(main)/problem/_components/SortButton.tsx
index eade0ed628..fe8f1cebdb 100644
--- a/apps/frontend/app/(client)/(main)/problem/_components/SortButton.tsx
+++ b/apps/frontend/app/(client)/(main)/problem/_components/SortButton.tsx
@@ -23,11 +23,13 @@ export default function SortButton({ children, order }: SortButtonProps) {
         const newParam = new URLSearchParams()
         // set all searchParam to newParam
         param.forEach((value, key) => newParam.set(key, value))
-        if (!currentOrder || !currentOrder.includes(order))
+        if (!currentOrder || !currentOrder.includes(order)) {
           newParam.set('order', `${order}-desc`)
-        else if (currentOrder == `${order}-desc`)
+        } else if (currentOrder === `${order}-desc`) {
           newParam.set('order', `${order}-asc`)
-        else if (currentOrder == `${order}-asc`) newParam.delete('order')
+        } else if (currentOrder === `${order}-asc`) {
+          newParam.delete('order')
+        }
         router.push(`${pathname}?${newParam.toString()}` as Route)
       }}
       className="items-center justify-center gap-1 md:text-base"
@@ -37,11 +39,11 @@ export default function SortButton({ children, order }: SortButtonProps) {
         <FaSortUp
           className={cn(
             'absolute',
-            currentOrder == `${order}-asc` && 'text-gray-900'
+            currentOrder === `${order}-asc` && 'text-gray-900'
           )}
         />
         <FaSortDown
-          className={cn(currentOrder == `${order}-desc` && 'text-gray-900')}
+          className={cn(currentOrder === `${order}-desc` && 'text-gray-900')}
         />
       </div>
     </Button>
diff --git a/apps/frontend/app/(client)/(main)/settings/_components/MajorSection.tsx b/apps/frontend/app/(client)/(main)/settings/_components/MajorSection.tsx
index a18dafcfe9..2e2c063030 100644
--- a/apps/frontend/app/(client)/(main)/settings/_components/MajorSection.tsx
+++ b/apps/frontend/app/(client)/(main)/settings/_components/MajorSection.tsx
@@ -27,6 +27,16 @@ export default function MajorSection() {
     defaultProfileValues
   } = useSettingsContext()
 
+  const getMajorDisplayValue = () => {
+    if (updateNow) {
+      return majorValue === 'none'
+        ? 'Department Information Unavailable / 학과 정보 없음'
+        : majorValue
+    }
+
+    return majorValue || defaultProfileValues.major
+  }
+
   return (
     <>
       <label className="-mb-4 mt-2 text-xs">First Major</label>
@@ -39,22 +49,19 @@ export default function MajorSection() {
               role="combobox"
               className={cn(
                 'justify-between border-gray-200 font-normal text-neutral-600 hover:bg-white',
-                updateNow
-                  ? `${majorValue === 'none' || isLoading ? 'border-red-500 text-neutral-400' : 'border-primary'}`
-                  : majorValue === defaultProfileValues.major
+                (() => {
+                  if (updateNow) {
+                    return majorValue === 'none' || isLoading
+                      ? 'border-red-500 text-neutral-400'
+                      : 'border-primary'
+                  }
+                  return majorValue === defaultProfileValues.major
                     ? 'text-neutral-400'
                     : 'border-primary'
+                })()
               )}
             >
-              {isLoading
-                ? 'Loading...'
-                : updateNow
-                  ? majorValue === 'none'
-                    ? 'Department Information Unavailable / 학과 정보 없음'
-                    : majorValue
-                  : !majorValue
-                    ? defaultProfileValues.major
-                    : majorValue}
+              {isLoading ? 'Loading...' : getMajorDisplayValue()}
               <FaChevronDown className="ml-2 h-4 w-4 shrink-0 opacity-50" />
             </Button>
           </PopoverTrigger>
diff --git a/apps/frontend/app/(client)/(main)/settings/_components/NameSection.tsx b/apps/frontend/app/(client)/(main)/settings/_components/NameSection.tsx
index d8a4714144..08373228ff 100644
--- a/apps/frontend/app/(client)/(main)/settings/_components/NameSection.tsx
+++ b/apps/frontend/app/(client)/(main)/settings/_components/NameSection.tsx
@@ -23,7 +23,7 @@ export default function NameSection({ realName }: NameSectionProps) {
             ? 'Loading...'
             : defaultProfileValues.userProfile?.realName || 'Enter your name'
         }
-        disabled={!!updateNow}
+        disabled={Boolean(updateNow)}
         {...register('realName')}
         className={cn(
           realName && (errors.realName ? 'border-red-500' : 'border-primary'),
diff --git a/apps/frontend/app/(client)/(main)/settings/_components/StudentIdSection.tsx b/apps/frontend/app/(client)/(main)/settings/_components/StudentIdSection.tsx
index fbe6c51b61..37f5be7fc6 100644
--- a/apps/frontend/app/(client)/(main)/settings/_components/StudentIdSection.tsx
+++ b/apps/frontend/app/(client)/(main)/settings/_components/StudentIdSection.tsx
@@ -13,26 +13,29 @@ export default function StudentIdSection({ studentId }: StudentIdSectionProps) {
     defaultProfileValues,
     formState: { register, errors }
   } = useSettingsContext()
+
   return (
     <>
       <label className="-mb-4 mt-2 text-xs">Student ID</label>
       <Input
-        placeholder={
-          updateNow
-            ? '2024123456'
-            : isLoading
-              ? 'Loading...'
-              : defaultProfileValues.studentId
-        }
+        placeholder={(() => {
+          if (updateNow) {
+            return '2024123456'
+          }
+          return isLoading ? 'Loading...' : defaultProfileValues.studentId
+        })()}
         disabled={!updateNow}
         {...register('studentId')}
         className={cn(
           'text-neutral-600 placeholder:text-neutral-400 focus-visible:ring-0',
-          updateNow
-            ? errors.studentId || !studentId
-              ? 'border-red-500'
-              : 'border-primary'
-            : 'border-neutral-300 disabled:bg-neutral-200'
+          (() => {
+            if (updateNow) {
+              return errors.studentId || !studentId
+                ? 'border-red-500'
+                : 'border-primary'
+            }
+            return 'border-neutral-300 disabled:bg-neutral-200'
+          })()
         )}
       />
       {errors.studentId && (
diff --git a/apps/frontend/app/(client)/(main)/settings/_libs/hooks/useCheckPassword.ts b/apps/frontend/app/(client)/(main)/settings/_libs/hooks/useCheckPassword.ts
index d5830d534e..80f46baa69 100644
--- a/apps/frontend/app/(client)/(main)/settings/_libs/hooks/useCheckPassword.ts
+++ b/apps/frontend/app/(client)/(main)/settings/_libs/hooks/useCheckPassword.ts
@@ -25,7 +25,7 @@ export const useCheckPassword = (
   const checkPassword = async () => {
     setIsCheckButtonClicked(true)
     try {
-      const response = await safeFetcher.post('auth/login', {
+      await safeFetcher.post('auth/login', {
         json: {
           username: defaultProfileValues.username,
           password: currentPassword
diff --git a/apps/frontend/app/(client)/(main)/settings/page.tsx b/apps/frontend/app/(client)/(main)/settings/page.tsx
index 0bcd37694b..99bc13e7e4 100644
--- a/apps/frontend/app/(client)/(main)/settings/page.tsx
+++ b/apps/frontend/app/(client)/(main)/settings/page.tsx
@@ -72,7 +72,7 @@ export default function Page() {
     watch,
     formState: { errors }
   } = useForm<SettingsFormat>({
-    resolver: zodResolver(schemaSettings(!!updateNow)),
+    resolver: zodResolver(schemaSettings(Boolean(updateNow))),
     mode: 'onChange',
     defaultValues: {
       currentPassword: '',
@@ -90,7 +90,7 @@ export default function Page() {
   const studentId = watch('studentId')
 
   const { isConfirmModalOpen, setIsConfirmModalOpen, confirmAction } =
-    useConfirmNavigation(bypassConfirmation, !!updateNow)
+    useConfirmNavigation(bypassConfirmation, Boolean(updateNow))
   const {
     isPasswordCorrect,
     newPasswordAble,
@@ -107,20 +107,20 @@ export default function Page() {
 
   const isPasswordsMatch = newPassword === confirmPassword && newPassword !== ''
   const saveAblePassword: boolean =
-    !!currentPassword &&
-    !!newPassword &&
-    !!confirmPassword &&
+    Boolean(currentPassword) &&
+    Boolean(newPassword) &&
+    Boolean(confirmPassword) &&
     isPasswordCorrect &&
     newPasswordAble &&
     isPasswordsMatch
   const saveAbleOthers: boolean =
-    !!realName || !!(majorValue !== defaultProfileValues.major)
+    Boolean(realName) || Boolean(majorValue !== defaultProfileValues.major)
   const saveAble =
     (saveAblePassword || saveAbleOthers) &&
     ((isPasswordsMatch && !errors.newPassword) ||
       (!newPassword && !confirmPassword))
   const saveAbleUpdateNow =
-    !!studentId && majorValue !== 'none' && !errors.studentId
+    Boolean(studentId) && majorValue !== 'none' && !errors.studentId
   // 일치 여부에 따라 New Password Input, Re-enter Password Input 창의 border 색상을 바꿈
   useEffect(() => {
     if (isPasswordsMatch) {
@@ -175,7 +175,9 @@ export default function Page() {
     value: string | undefined,
     defaultValue: string
   ) => {
-    if (value === '') setValue(field, defaultValue)
+    if (value === '') {
+      setValue(field, defaultValue)
+    }
   }
 
   const onSubmitClick = () => {
@@ -209,7 +211,7 @@ export default function Page() {
       register,
       errors
     },
-    updateNow: !!updateNow,
+    updateNow: Boolean(updateNow),
     isLoading
   }
 
diff --git a/apps/frontend/app/(handler)/next-auth/api/auth/[...nextauth]/route.ts b/apps/frontend/app/(handler)/next-auth/api/auth/[...nextauth]/route.ts
index 9cb99cb548..68fb4ac9db 100644
--- a/apps/frontend/app/(handler)/next-auth/api/auth/[...nextauth]/route.ts
+++ b/apps/frontend/app/(handler)/next-auth/api/auth/[...nextauth]/route.ts
@@ -6,7 +6,7 @@ interface RouteHandlerContext {
   params: { nextauth: string[] }
 }
 
-const handler = async (req: NextRequest, res: RouteHandlerContext) => {
+const handler = (req: NextRequest, res: RouteHandlerContext) => {
   return NextAuth(req, res, authOptions)
 }
 
diff --git a/apps/frontend/app/admin/_components/SwitchField.tsx b/apps/frontend/app/admin/_components/SwitchField.tsx
index a0c899cc1f..fc50ba8f5a 100644
--- a/apps/frontend/app/admin/_components/SwitchField.tsx
+++ b/apps/frontend/app/admin/_components/SwitchField.tsx
@@ -46,9 +46,13 @@ export default function SwitchField({
         <Label required={false}>{title}</Label>
         <Switch
           onCheckedChange={() => {
-            if (name == 'invitationCode') setValue(name, null)
-            else if (name == 'hint' || name == 'source') setValue(name, '')
-            else setValue(name, !getValues(name))
+            if (name === 'invitationCode') {
+              setValue(name, null)
+            } else if (name === 'hint' || name === 'source') {
+              setValue(name, '')
+            } else {
+              setValue(name, !getValues(name))
+            }
             setIsEnabled(!isEnabled)
           }}
           checked={isEnabled}
@@ -56,25 +60,38 @@ export default function SwitchField({
         />
       </div>
       {isEnabled &&
-        (formElement == 'input' ? (
-          <Input
-            id={name}
-            type={type}
-            placeholder={placeholder}
-            className={cn(inputStyle, 'hide-spin-button h-[36px] w-[380px]')}
-            {...register(name, {
-              onChange: () => trigger(name)
-            })}
-          />
-        ) : formElement == 'textarea' ? (
-          <Textarea
-            id={name}
-            placeholder={placeholder}
-            className="min-h-[120px] w-[760px] bg-white"
-            {...register(name)}
-          />
-        ) : null)}
-      {isEnabled && name == 'invitationCode' && errors[name] && (
+        (() => {
+          if (formElement === 'input') {
+            return (
+              <Input
+                id={name}
+                type={type}
+                placeholder={placeholder}
+                className={cn(
+                  inputStyle,
+                  'hide-spin-button h-[36px] w-[380px]'
+                )}
+                {...register(name, {
+                  onChange: () => trigger(name)
+                })}
+              />
+            )
+          }
+
+          if (formElement === 'textarea') {
+            return (
+              <Textarea
+                id={name}
+                placeholder={placeholder}
+                className="min-h-[120px] w-[760px] bg-white"
+                {...register(name)}
+              />
+            )
+          }
+
+          return null
+        })()}
+      {isEnabled && name === 'invitationCode' && errors[name] && (
         <ErrorMessage message={errors[name]?.message?.toString()} />
       )}
     </div>
diff --git a/apps/frontend/app/admin/_components/table/DataTableColumnHeader.tsx b/apps/frontend/app/admin/_components/table/DataTableColumnHeader.tsx
index 04f2c4611e..c90541cfb6 100644
--- a/apps/frontend/app/admin/_components/table/DataTableColumnHeader.tsx
+++ b/apps/frontend/app/admin/_components/table/DataTableColumnHeader.tsx
@@ -50,16 +50,21 @@ export default function DataTableColumnHeader<TData, TValue>({
             )}
           >
             <span>{title}</span>
-            {column.getIsSorted() === 'desc' ? (
-              <TriangleDownIcon className="ml-2 h-4 w-4" />
-            ) : column.getIsSorted() === 'asc' ? (
-              <TriangleUpIcon className="ml-2 h-4 w-4" />
-            ) : (
-              <div>
-                <TriangleUpIcon className="-mb-2.5 ml-2 h-4 w-4" />
-                <TriangleDownIcon className="-mt- ml-2 h-4 w-4" />
-              </div>
-            )}
+            {(() => {
+              const sort = column.getIsSorted()
+              if (sort === 'desc') {
+                return <TriangleDownIcon className="ml-2 h-4 w-4" />
+              }
+              if (sort === 'asc') {
+                return <TriangleUpIcon className="ml-2 h-4 w-4" />
+              }
+              return (
+                <div>
+                  <TriangleUpIcon className="-mb-2.5 ml-2 h-4 w-4" />
+                  <TriangleDownIcon className="-mt- ml-2 h-4 w-4" />
+                </div>
+              )
+            })()}
           </Button>
         </DropdownMenuTrigger>
         <DropdownMenuContent align="start">
diff --git a/apps/frontend/app/admin/_components/table/DataTableDeleteButton.tsx b/apps/frontend/app/admin/_components/table/DataTableDeleteButton.tsx
index 9320bbc5ab..e8f4ef89e1 100644
--- a/apps/frontend/app/admin/_components/table/DataTableDeleteButton.tsx
+++ b/apps/frontend/app/admin/_components/table/DataTableDeleteButton.tsx
@@ -53,7 +53,9 @@ export default function DataTableDeleteButton<
   const [isDialogOpen, setIsDialogOpen] = useState(false)
 
   const handleDeleteButtonClick = async () => {
-    if (table.getSelectedRowModel().rows.length === 0) return
+    if (table.getSelectedRowModel().rows.length === 0) {
+      return
+    }
 
     if (!getCanDelete) {
       setIsDialogOpen(true)
diff --git a/apps/frontend/app/admin/_components/table/DataTableMultiSelectFilter.tsx b/apps/frontend/app/admin/_components/table/DataTableMultiSelectFilter.tsx
index 0e820d2272..b91a8728bc 100644
--- a/apps/frontend/app/admin/_components/table/DataTableMultiSelectFilter.tsx
+++ b/apps/frontend/app/admin/_components/table/DataTableMultiSelectFilter.tsx
@@ -127,7 +127,11 @@ export default function DataTableMultiSelectFilter<TData, TValue>({
 }
 
 const getSelectedValues = (data: unknown): Set<string> => {
-  if (!Array.isArray(data)) return new Set()
-  if (data.every((item) => typeof item === 'string')) return new Set(data)
+  if (!Array.isArray(data)) {
+    return new Set()
+  }
+  if (data.every((item) => typeof item === 'string')) {
+    return new Set(data)
+  }
   return new Set()
 }
diff --git a/apps/frontend/app/admin/_components/table/DataTableProblemFilter.tsx b/apps/frontend/app/admin/_components/table/DataTableProblemFilter.tsx
index 2ec1b73ae7..8b50fdfa29 100644
--- a/apps/frontend/app/admin/_components/table/DataTableProblemFilter.tsx
+++ b/apps/frontend/app/admin/_components/table/DataTableProblemFilter.tsx
@@ -107,6 +107,8 @@ export default function DataTableProblemFilter({
 }
 
 const getSelectedValue = (data: unknown): string | null => {
-  if (typeof data !== 'string') return null
+  if (typeof data !== 'string') {
+    return null
+  }
   return data
 }
diff --git a/apps/frontend/app/admin/contest/[contestId]/_components/ContestOverallTabs.tsx b/apps/frontend/app/admin/contest/[contestId]/_components/ContestOverallTabs.tsx
index b705044b44..84c766df1e 100644
--- a/apps/frontend/app/admin/contest/[contestId]/_components/ContestOverallTabs.tsx
+++ b/apps/frontend/app/admin/contest/[contestId]/_components/ContestOverallTabs.tsx
@@ -145,7 +145,9 @@ export default function ContestOverallTabs({
     }) || []
 
   const isCurrentTab = (tab: string) => {
-    if (tab === '') return pathname === `/admin/contest/${id}`
+    if (tab === '') {
+      return pathname === `/admin/contest/${id}`
+    }
     return pathname.startsWith(`/admin/contest/${id}/${tab}`)
   }
 
diff --git a/apps/frontend/app/admin/contest/[contestId]/_components/SubmissionDetailAdmin.tsx b/apps/frontend/app/admin/contest/[contestId]/_components/SubmissionDetailAdmin.tsx
index 63dee729f7..cc308d1d72 100644
--- a/apps/frontend/app/admin/contest/[contestId]/_components/SubmissionDetailAdmin.tsx
+++ b/apps/frontend/app/admin/contest/[contestId]/_components/SubmissionDetailAdmin.tsx
@@ -155,7 +155,7 @@ export default function SubmissionDetailAdmin({
               <Table className="[&_*]:text-center [&_*]:text-xs [&_*]:hover:bg-transparent [&_td]:p-2 [&_tr]:!border-neutral-200">
                 <TableHeader>
                   <TableRow>
-                    <TableHead></TableHead>
+                    <TableHead />
                     <TableHead className="!text-sm text-black">
                       Result
                     </TableHead>
diff --git a/apps/frontend/app/admin/contest/_components/ContestTableColumns.tsx b/apps/frontend/app/admin/contest/_components/ContestTableColumns.tsx
index f41ff97c31..586345d8bf 100644
--- a/apps/frontend/app/admin/contest/_components/ContestTableColumns.tsx
+++ b/apps/frontend/app/admin/contest/_components/ContestTableColumns.tsx
@@ -122,7 +122,9 @@ export const columns: ColumnDef<DataTableContest>[] = [
       <Checkbox
         onClick={(e) => e.stopPropagation()}
         checked={table.getIsAllPageRowsSelected()}
-        onCheckedChange={(value) => table.toggleAllPageRowsSelected(!!value)}
+        onCheckedChange={(value) =>
+          table.toggleAllPageRowsSelected(Boolean(value))
+        }
         aria-label="Select all"
         className="translate-y-[2px] bg-white"
       />
@@ -131,7 +133,7 @@ export const columns: ColumnDef<DataTableContest>[] = [
       <Checkbox
         onClick={(e) => e.stopPropagation()}
         checked={row.getIsSelected()}
-        onCheckedChange={(value) => row.toggleSelected(!!value)}
+        onCheckedChange={(value) => row.toggleSelected(Boolean(value))}
         aria-label="Select row"
         className="translate-y-[2px] bg-white"
       />
diff --git a/apps/frontend/app/admin/contest/_components/DuplicateContestButton.tsx b/apps/frontend/app/admin/contest/_components/DuplicateContestButton.tsx
index d7e18b56cd..0f19886d20 100644
--- a/apps/frontend/app/admin/contest/_components/DuplicateContestButton.tsx
+++ b/apps/frontend/app/admin/contest/_components/DuplicateContestButton.tsx
@@ -75,7 +75,7 @@ function EnabledDuplicateButton({
   const client = useApolloClient()
   const [duplicateContest] = useMutation(DUPLICATE_CONTEST)
 
-  const duplicateContestById = async () => {
+  const duplicateContestById = () => {
     const toastId = toast.loading('Duplicating contest...')
 
     duplicateContest({
diff --git a/apps/frontend/app/admin/contest/_components/ImportProblemTable.tsx b/apps/frontend/app/admin/contest/_components/ImportProblemTable.tsx
index 1cac1c6b1e..5e6b7c8465 100644
--- a/apps/frontend/app/admin/contest/_components/ImportProblemTable.tsx
+++ b/apps/frontend/app/admin/contest/_components/ImportProblemTable.tsx
@@ -48,7 +48,7 @@ export function ImportProblemTable({
     isVisible: problem.isVisible !== undefined ? problem.isVisible : null,
     languages: problem.languages ?? [],
     tag: problem.tag.map(({ id, tag }) => ({
-      id: +id,
+      id: Number(id),
       tag: {
         ...tag,
         id: Number(tag.id)
diff --git a/apps/frontend/app/admin/notice/_components/CreateNoticeForm.tsx b/apps/frontend/app/admin/notice/_components/CreateNoticeForm.tsx
index 9facaf5186..5a8c572a15 100644
--- a/apps/frontend/app/admin/notice/_components/CreateNoticeForm.tsx
+++ b/apps/frontend/app/admin/notice/_components/CreateNoticeForm.tsx
@@ -49,10 +49,8 @@ export default function CreateNoticeForm({ children }: CreateNoticeFormProps) {
   })
 
   return (
-    <>
-      <form className="flex w-[760px] flex-col gap-6" onSubmit={onSubmit}>
-        <FormProvider {...methods}>{children}</FormProvider>
-      </form>
-    </>
+    <form className="flex w-[760px] flex-col gap-6" onSubmit={onSubmit}>
+      <FormProvider {...methods}>{children}</FormProvider>
+    </form>
   )
 }
diff --git a/apps/frontend/app/admin/problem/[problemId]/edit/_components/BelongedContestTableColumns.tsx b/apps/frontend/app/admin/problem/[problemId]/edit/_components/BelongedContestTableColumns.tsx
index b5d19dfe4b..63c79485d8 100644
--- a/apps/frontend/app/admin/problem/[problemId]/edit/_components/BelongedContestTableColumns.tsx
+++ b/apps/frontend/app/admin/problem/[problemId]/edit/_components/BelongedContestTableColumns.tsx
@@ -21,7 +21,9 @@ export const columns: ColumnDef<BelongedContest>[] = [
       <Checkbox
         onClick={(e) => e.stopPropagation()}
         checked={table.getIsAllPageRowsSelected()}
-        onCheckedChange={(value) => table.toggleAllPageRowsSelected(!!value)}
+        onCheckedChange={(value) =>
+          table.toggleAllPageRowsSelected(Boolean(value))
+        }
         aria-label="Select all"
         className="translate-y-[2px] bg-white"
       />
@@ -30,7 +32,7 @@ export const columns: ColumnDef<BelongedContest>[] = [
       <Checkbox
         onClick={(e) => e.stopPropagation()}
         checked={row.getIsSelected()}
-        onCheckedChange={(value) => row.toggleSelected(!!value)}
+        onCheckedChange={(value) => row.toggleSelected(Boolean(value))}
         aria-label="Select row"
         className="translate-y-[2px] bg-white"
       />
diff --git a/apps/frontend/app/admin/problem/[problemId]/edit/_components/RevertScoreButton.tsx b/apps/frontend/app/admin/problem/[problemId]/edit/_components/RevertScoreButton.tsx
index 032fb6fde6..99ccb85595 100644
--- a/apps/frontend/app/admin/problem/[problemId]/edit/_components/RevertScoreButton.tsx
+++ b/apps/frontend/app/admin/problem/[problemId]/edit/_components/RevertScoreButton.tsx
@@ -13,20 +13,16 @@ export default function RevertScoreButton({
 
   const selectedContests = table.getSelectedRowModel().rows
 
-  return (
-    <>
-      {selectedContests.length > 0 && (
-        <Button
-          onClick={() => {
-            table.resetRowSelection()
-            onRevertScore()
-          }}
-          variant="filter"
-          className="ml-3"
-        >
-          Revert Score
-        </Button>
-      )}
-    </>
-  )
+  return selectedContests.length > 0 ? (
+    <Button
+      onClick={() => {
+        table.resetRowSelection()
+        onRevertScore()
+      }}
+      variant="filter"
+      className="ml-3"
+    >
+      Revert Score
+    </Button>
+  ) : null
 }
diff --git a/apps/frontend/app/admin/problem/[problemId]/edit/_components/ScoreCautionDialog.tsx b/apps/frontend/app/admin/problem/[problemId]/edit/_components/ScoreCautionDialog.tsx
index 85c6bed62a..6f95648a00 100644
--- a/apps/frontend/app/admin/problem/[problemId]/edit/_components/ScoreCautionDialog.tsx
+++ b/apps/frontend/app/admin/problem/[problemId]/edit/_components/ScoreCautionDialog.tsx
@@ -78,7 +78,7 @@ export function ScoreCautionDialog({
                     problemId={problemId}
                     onSetToZero={(contests) => setZeroSetContests(contests)}
                     onRevertScore={() => setZeroSetContests([])}
-                  ></BelongedContestTable>
+                  />
                 </Suspense>
                 <div className="my-4 border-b" />
               </li>
diff --git a/apps/frontend/app/admin/problem/[problemId]/edit/_components/SetToZeroButton.tsx b/apps/frontend/app/admin/problem/[problemId]/edit/_components/SetToZeroButton.tsx
index d6ac279638..893b0116e4 100644
--- a/apps/frontend/app/admin/problem/[problemId]/edit/_components/SetToZeroButton.tsx
+++ b/apps/frontend/app/admin/problem/[problemId]/edit/_components/SetToZeroButton.tsx
@@ -13,13 +13,9 @@ export default function SetToZeroButton({ onSetToZero }: SetToZeroButtonProps) {
     .getSelectedRowModel()
     .rows.map((row) => row.original.id)
 
-  return (
-    <>
-      {selectedContests.length > 0 && (
-        <Button onClick={() => onSetToZero(selectedContests)} variant="outline">
-          Set to Zero
-        </Button>
-      )}
-    </>
-  )
+  return selectedContests.length > 0 ? (
+    <Button onClick={() => onSetToZero(selectedContests)} variant="outline">
+      Set to Zero
+    </Button>
+  ) : null
 }
diff --git a/apps/frontend/app/admin/problem/[problemId]/edit/page.tsx b/apps/frontend/app/admin/problem/[problemId]/edit/page.tsx
index c4e6441894..e0acbdbf6e 100644
--- a/apps/frontend/app/admin/problem/[problemId]/edit/page.tsx
+++ b/apps/frontend/app/admin/problem/[problemId]/edit/page.tsx
@@ -98,9 +98,13 @@ export default function Page({ params }: { params: { problemId: string } }) {
       setValue('timeLimit', data.timeLimit)
       setValue('memoryLimit', data.memoryLimit)
       setValue('hint', data.hint)
-      if (data.hint !== '') setShowHint(true)
+      if (data.hint !== '') {
+        setShowHint(true)
+      }
       setValue('source', data.source)
-      if (data.source !== '') setShowSource(true)
+      if (data.source !== '') {
+        setShowSource(true)
+      }
       if (data.template) {
         const templates = JSON.parse(data.template[0])
         templates.map((template: Template, index: number) => {
diff --git a/apps/frontend/app/admin/problem/_components/CheckboxSelect.tsx b/apps/frontend/app/admin/problem/_components/CheckboxSelect.tsx
index f46055162f..c38657dcfa 100644
--- a/apps/frontend/app/admin/problem/_components/CheckboxSelect.tsx
+++ b/apps/frontend/app/admin/problem/_components/CheckboxSelect.tsx
@@ -100,7 +100,7 @@ export default function LanguageSelect<T extends string>({
                   <Checkbox
                     checked={selectedValues.includes(option)}
                     onCheckedChange={() => handleCheckboxChange(option)}
-                  ></Checkbox>
+                  />
                   {option}
                 </CommandItem>
               ))}
diff --git a/apps/frontend/app/admin/problem/_components/ContainedContests.tsx b/apps/frontend/app/admin/problem/_components/ContainedContests.tsx
index 3b75ecea3e..38e2d145c2 100644
--- a/apps/frontend/app/admin/problem/_components/ContainedContests.tsx
+++ b/apps/frontend/app/admin/problem/_components/ContainedContests.tsx
@@ -25,7 +25,9 @@ function ContestSection({
   title: string
   contests?: { id: string; title: string }[]
 }) {
-  if (!contests || contests.length === 0) return null
+  if (!contests || contests.length === 0) {
+    return null
+  }
 
   return (
     <div>
diff --git a/apps/frontend/app/admin/problem/_components/InfoForm.tsx b/apps/frontend/app/admin/problem/_components/InfoForm.tsx
index 93ba4201bb..8a8a009a4d 100644
--- a/apps/frontend/app/admin/problem/_components/InfoForm.tsx
+++ b/apps/frontend/app/admin/problem/_components/InfoForm.tsx
@@ -25,7 +25,7 @@ export default function InfoForm() {
       const templates: Template[] = [] // temp array to store templates
       const savedTemplates: Template[] = getValues('template') // templates saved in form
       watchedLanguages.map((language) => {
-        const temp = savedTemplates!.filter(
+        const temp = savedTemplates.filter(
           (template) => template.language === language
         )
         if (temp.length !== 0) {
diff --git a/apps/frontend/app/admin/problem/_components/ProblemTable.tsx b/apps/frontend/app/admin/problem/_components/ProblemTable.tsx
index 8a3e62acc3..9aada240ca 100644
--- a/apps/frontend/app/admin/problem/_components/ProblemTable.tsx
+++ b/apps/frontend/app/admin/problem/_components/ProblemTable.tsx
@@ -35,7 +35,7 @@ export function ProblemTable() {
     isVisible: problem.isVisible !== undefined ? problem.isVisible : null,
     languages: problem.languages ?? [],
     tag: problem.tag.map(({ id, tag }) => ({
-      id: +id,
+      id: Number(id),
       tag: {
         ...tag,
         id: Number(tag.id)
diff --git a/apps/frontend/app/admin/problem/_components/ProblemTableColumns.tsx b/apps/frontend/app/admin/problem/_components/ProblemTableColumns.tsx
index bb4168a43f..f51bc48760 100644
--- a/apps/frontend/app/admin/problem/_components/ProblemTableColumns.tsx
+++ b/apps/frontend/app/admin/problem/_components/ProblemTableColumns.tsx
@@ -59,7 +59,9 @@ export const columns: ColumnDef<DataTableProblem>[] = [
     header: ({ table }) => (
       <Checkbox
         checked={table.getIsAllPageRowsSelected()}
-        onCheckedChange={(value) => table.toggleAllPageRowsSelected(!!value)}
+        onCheckedChange={(value) =>
+          table.toggleAllPageRowsSelected(Boolean(value))
+        }
         aria-label="Select all"
         className="translate-y-[2px]"
       />
@@ -68,7 +70,7 @@ export const columns: ColumnDef<DataTableProblem>[] = [
       <Checkbox
         onClick={(e) => e.stopPropagation()}
         checked={row.getIsSelected()}
-        onCheckedChange={(value) => row.toggleSelected(!!value)}
+        onCheckedChange={(value) => row.toggleSelected(Boolean(value))}
         aria-label="Select row"
         className="translate-y-[2px]"
       />
diff --git a/apps/frontend/app/admin/problem/_components/TestcaseField.tsx b/apps/frontend/app/admin/problem/_components/TestcaseField.tsx
index 95f52aafea..858400cacb 100644
--- a/apps/frontend/app/admin/problem/_components/TestcaseField.tsx
+++ b/apps/frontend/app/admin/problem/_components/TestcaseField.tsx
@@ -70,13 +70,13 @@ export default function TestcaseField({
       .map((tc) => tc.scoreWeight)
       .filter((score) => !isInvalid(score))
       .reduce((acc: number, score) => {
-        if (score! < 0) {
+        if (score < 0) {
           setDialogDescription(
             'The scoring ratios contain negative value(s).\nPlease review and correct them.'
           )
           setDialogOpen(true)
         }
-        return acc + score!
+        return acc + score
       }, 0)
 
     const remainingScore = 100 - totalAssignedScore
diff --git a/apps/frontend/app/admin/problem/_components/TestcaseItem.tsx b/apps/frontend/app/admin/problem/_components/TestcaseItem.tsx
index 6e9c2b3d70..524634ffb4 100644
--- a/apps/frontend/app/admin/problem/_components/TestcaseItem.tsx
+++ b/apps/frontend/app/admin/problem/_components/TestcaseItem.tsx
@@ -47,7 +47,7 @@ export default function TestcaseItem({
               <p
                 className={cn(
                   'text-sm',
-                  isHiddenField.value == false
+                  isHiddenField.value === false
                     ? 'font-medium text-gray-500'
                     : 'text-gray-400'
                 )}
@@ -66,7 +66,7 @@ export default function TestcaseItem({
               <p
                 className={cn(
                   'text-sm',
-                  isHiddenField.value == true
+                  isHiddenField.value === true
                     ? 'font-medium text-gray-500'
                     : 'text-gray-400'
                 )}
diff --git a/apps/frontend/app/admin/problem/_components/UploadDialog.tsx b/apps/frontend/app/admin/problem/_components/UploadDialog.tsx
index 9fe04f1d51..34db7a6796 100644
--- a/apps/frontend/app/admin/problem/_components/UploadDialog.tsx
+++ b/apps/frontend/app/admin/problem/_components/UploadDialog.tsx
@@ -46,7 +46,9 @@ export default function UploadDialog() {
 
   const resetFile = () => {
     setFile(null)
-    if (fileRef.current) fileRef.current.value = ''
+    if (fileRef.current) {
+      fileRef.current.value = ''
+    }
   }
 
   const [uploadProblems, { loading }] = useMutation(UPLOAD_PROBLEMS)
diff --git a/apps/frontend/app/admin/problem/_libs/utils.ts b/apps/frontend/app/admin/problem/_libs/utils.ts
index 2f9b83f9e7..6d0086b6a2 100644
--- a/apps/frontend/app/admin/problem/_libs/utils.ts
+++ b/apps/frontend/app/admin/problem/_libs/utils.ts
@@ -9,7 +9,7 @@ export const isInvalid = (value: Invalid) => {
 export const validateScoreWeight = (testcases: Testcase[]): boolean => {
   const totalScore = testcases
     .map((tc: Testcase) => tc.scoreWeight)
-    .reduce((acc: number, score) => acc + score!, 0)
+    .reduce((acc: number, score) => acc + score, 0)
 
   return totalScore === 100
 }
diff --git a/apps/frontend/app/admin/problem/create/_components/CreateProblemForm.tsx b/apps/frontend/app/admin/problem/create/_components/CreateProblemForm.tsx
index 02515a17a6..d31be6cb84 100644
--- a/apps/frontend/app/admin/problem/create/_components/CreateProblemForm.tsx
+++ b/apps/frontend/app/admin/problem/create/_components/CreateProblemForm.tsx
@@ -69,7 +69,9 @@ export default function CreateProblemForm({
   }
 
   const onSubmit = methods.handleSubmit(async () => {
-    if (!validate()) return
+    if (!validate()) {
+      return
+    }
     const input = methods.getValues()
     await createProblem({
       variables: {
diff --git a/apps/frontend/components/ContestStatusTimeDiff.tsx b/apps/frontend/components/ContestStatusTimeDiff.tsx
index b7405f90db..34d1c1385c 100644
--- a/apps/frontend/components/ContestStatusTimeDiff.tsx
+++ b/apps/frontend/components/ContestStatusTimeDiff.tsx
@@ -54,11 +54,11 @@ export default function ContestStatusTimeDiff({
     const diff = dayjs.duration(Math.abs(dayjs(timeRef).diff(now)))
     const days = Math.floor(diff.asDays())
     const hours = Math.floor(diff.asHours() % 24)
-    const hours_str = hours.toString().padStart(2, '0')
+    const hoursStr = hours.toString().padStart(2, '0')
     const minutes = Math.floor(diff.asMinutes() % 60)
-    const minutes_str = minutes.toString().padStart(2, '0')
+    const minutesStr = minutes.toString().padStart(2, '0')
     const seconds = Math.floor(diff.asSeconds() % 60)
-    const seconds_str = seconds.toString().padStart(2, '0')
+    const secondsStr = seconds.toString().padStart(2, '0')
 
     if (inContestEditor) {
       if (days === 0 && hours === 0 && minutes === 5 && seconds === 0) {
@@ -71,9 +71,9 @@ export default function ContestStatusTimeDiff({
 
     setTimeDiff({
       days,
-      hours: hours_str,
-      minutes: minutes_str,
-      seconds: seconds_str
+      hours: hoursStr,
+      minutes: minutesStr,
+      seconds: secondsStr
     })
   }
 
diff --git a/apps/frontend/components/KatexContent.tsx b/apps/frontend/components/KatexContent.tsx
index 601c01280b..29fbebb43b 100644
--- a/apps/frontend/components/KatexContent.tsx
+++ b/apps/frontend/components/KatexContent.tsx
@@ -10,7 +10,7 @@ export default function KatexContent({
   content: string | undefined
   classname?: string
 }) {
-  const katexRef = useRef<HTMLDivElement>(null)!
+  const katexRef = useRef<HTMLDivElement>(null)
   useEffect(() => {
     renderKatex(content, katexRef)
   }, [content, katexRef])
diff --git a/apps/frontend/components/Paginator.tsx b/apps/frontend/components/Paginator.tsx
index f139e75ccf..27d64838dc 100644
--- a/apps/frontend/components/Paginator.tsx
+++ b/apps/frontend/components/Paginator.tsx
@@ -28,7 +28,7 @@ export default function Paginator({ page, slot }: Props) {
           onClick={() => {
             slot.goto('prev')
           }}
-          isActive={!!slot.prev}
+          isActive={Boolean(slot.prev)}
         />
         <div className="flex items-center gap-1">
           {Array.from({ length: page.count }).map((_, i) => {
@@ -50,7 +50,7 @@ export default function Paginator({ page, slot }: Props) {
           onClick={() => {
             slot.goto('next')
           }}
-          isActive={!!slot.next}
+          isActive={Boolean(slot.next)}
         />
       </PaginationContent>
     </Pagination>
diff --git a/apps/frontend/components/TextEditor.tsx b/apps/frontend/components/TextEditor.tsx
index d2f0de9a77..6091c70674 100644
--- a/apps/frontend/components/TextEditor.tsx
+++ b/apps/frontend/components/TextEditor.tsx
@@ -200,7 +200,9 @@ export default function TextEditor({
   const setLink = useCallback(
     (linkUrl: string | null) => {
       console.log(linkUrl)
-      if (!editor) return null
+      if (!editor) {
+        return null
+      }
       // cancelled
       if (linkUrl === null) {
         return
@@ -224,7 +226,9 @@ export default function TextEditor({
   const addImage = useCallback(
     (imageUrl: string | undefined) => {
       console.log(imageUrl)
-      if (!editor) return null
+      if (!editor) {
+        return null
+      }
       if (imageUrl === null) {
         return
       }
@@ -241,7 +245,9 @@ export default function TextEditor({
   const [uploadImage] = useMutation(UPLOAD_IMAGE)
 
   const handleUploadPhoto = async (files: FileList | null) => {
-    if (files === null) return
+    if (files === null) {
+      return
+    }
     const file = files[0]
     try {
       const { data } = await uploadImage({
diff --git a/apps/frontend/components/auth/FindUserId.tsx b/apps/frontend/components/auth/FindUserId.tsx
index 4fa44f0103..4502418593 100644
--- a/apps/frontend/components/auth/FindUserId.tsx
+++ b/apps/frontend/components/auth/FindUserId.tsx
@@ -103,7 +103,7 @@ export default function FindUserId() {
             type="email"
             className={cn(
               inputFocused && 'ring-1 focus-visible:ring-1 disabled:ring-0',
-              errors.email || (emailError && getValues('email') == wrongEmail)
+              errors.email || (emailError && getValues('email') === wrongEmail)
                 ? 'ring-red-500 focus-visible:ring-red-500'
                 : 'focus-visible:ring-primary'
             )}
@@ -113,12 +113,12 @@ export default function FindUserId() {
             })}
             onFocus={() => setInputFocused(true)}
             onBlur={() => trigger('email')}
-            disabled={!!userId}
+            disabled={Boolean(userId)}
           />
           {errors.email && (
             <p className="text-xs text-red-500">{errors.email?.message}</p>
           )}
-          {emailError && getValues('email') == wrongEmail && (
+          {emailError && getValues('email') === wrongEmail && (
             <p className="text-xs text-red-500">{emailError}</p>
           )}
           {userId && (
diff --git a/apps/frontend/components/auth/HeaderAuthPanel.tsx b/apps/frontend/components/auth/HeaderAuthPanel.tsx
index b0a2e8c4a3..b02836d7ad 100644
--- a/apps/frontend/components/auth/HeaderAuthPanel.tsx
+++ b/apps/frontend/components/auth/HeaderAuthPanel.tsx
@@ -28,12 +28,7 @@ import UpdateInformation from './UpdateInformation'
 
 interface HeaderAuthPanelProps {
   session: Session | null
-  group?: keyof typeof variants
-}
-
-const variants: { [key: string]: 'outline' | 'slate' } = {
-  default: 'outline',
-  editor: 'slate'
+  group?: 'default' | 'editor'
 }
 
 export default function HeaderAuthPanel({
diff --git a/apps/frontend/components/auth/SignUpEmailVerify.tsx b/apps/frontend/components/auth/SignUpEmailVerify.tsx
index e2570a9dc8..a2248234ff 100644
--- a/apps/frontend/components/auth/SignUpEmailVerify.tsx
+++ b/apps/frontend/components/auth/SignUpEmailVerify.tsx
@@ -95,7 +95,7 @@ export default function SignUpEmailVerify() {
     setEmailError('')
     await trigger('email')
     if (!errors.email) {
-      await fetch(baseUrl + '/email-auth/send-email/register-new', {
+      await fetch(`${baseUrl}/email-auth/send-email/register-new`, {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ email })
@@ -121,7 +121,7 @@ export default function SignUpEmailVerify() {
     await trigger('verificationCode')
     if (!errors.verificationCode) {
       try {
-        const response = await fetch(baseUrl + '/email-auth/verify-pin', {
+        const response = await fetch(`${baseUrl}/email-auth/verify-pin`, {
           method: 'POST',
           headers: { 'Content-Type': 'application/json' },
           credentials: 'include',
@@ -166,7 +166,7 @@ export default function SignUpEmailVerify() {
             placeholder="example@g.skku.edu"
             {...register('email')}
             onFocus={() => clearErrors('email')}
-            onKeyDown={async (e) => {
+            onKeyDown={(e) => {
               if (e.key === 'Enter' && !sendButtonDisabled) {
                 e.preventDefault()
                 setSendButtonDisabled(true)
@@ -228,42 +228,52 @@ export default function SignUpEmailVerify() {
           )}
         </div>
       )}
+      {(() => {
+        if (!sentEmail) {
+          return (
+            <Button
+              type="button"
+              className="mt-4 w-full font-semibold"
+              disabled={sendButtonDisabled}
+              onClick={() => {
+                setSendButtonDisabled(true)
+                sendEmail()
+              }}
+            >
+              Send Email
+            </Button>
+          )
+        }
 
-      {!sentEmail ? (
-        <Button
-          type="button"
-          className="mt-4 w-full font-semibold"
-          disabled={sendButtonDisabled}
-          onClick={() => {
-            setSendButtonDisabled(true)
-            sendEmail()
-          }}
-        >
-          Send Email
-        </Button>
-      ) : !expired ? (
-        <Button
-          type="submit"
-          className={cn(
-            'mt-2 w-full font-semibold',
-            (!emailVerified || !!errors.verificationCode) && 'bg-gray-400'
-          )}
-          disabled={!emailVerified || !!errors.verificationCode}
-        >
-          Next
-        </Button>
-      ) : (
-        <Button
-          className="mt-2 w-full font-semibold"
-          onClick={() => {
-            setExpired(false)
-            setTimer(timeLimit)
-            sendEmail()
-          }}
-        >
-          Resend Email
-        </Button>
-      )}
+        if (!expired) {
+          return (
+            <Button
+              type="submit"
+              className={cn(
+                'mt-2 w-full font-semibold',
+                (!emailVerified || Boolean(errors.verificationCode)) &&
+                  'bg-gray-400'
+              )}
+              disabled={!emailVerified || Boolean(errors.verificationCode)}
+            >
+              Next
+            </Button>
+          )
+        }
+
+        return (
+          <Button
+            className="mt-2 w-full font-semibold"
+            onClick={() => {
+              setExpired(false)
+              setTimer(timeLimit)
+              sendEmail()
+            }}
+          >
+            Resend Email
+          </Button>
+        )
+      })()}
     </form>
   )
 }
diff --git a/apps/frontend/components/auth/SignUpRegister.tsx b/apps/frontend/components/auth/SignUpRegister.tsx
index 2de03b3fb2..3e5c280b3b 100644
--- a/apps/frontend/components/auth/SignUpRegister.tsx
+++ b/apps/frontend/components/auth/SignUpRegister.tsx
@@ -182,7 +182,7 @@ export default function SignUpRegister() {
     const fullName = `${data.firstName} ${data.lastName}`
     try {
       setSignUpDisable(true)
-      await fetch(baseUrl + '/user/sign-up', {
+      await fetch(`${baseUrl}/user/sign-up`, {
         method: 'POST',
         headers: {
           ...formData.headers,
@@ -218,7 +218,7 @@ export default function SignUpRegister() {
     await trigger('username')
     if (!errors.username) {
       try {
-        await fetch(baseUrl + `/user/username-check?username=${username}`, {
+        await fetch(`${baseUrl}/user/username-check?username=${username}`, {
           method: 'GET'
         }).then((res) => {
           setCheckedUsername(username)
@@ -260,13 +260,12 @@ export default function SignUpRegister() {
               placeholder="User ID"
               className={cn(
                 'focus-visible:ring-0',
-                !focusedList[1]
-                  ? ''
-                  : errors.username &&
-                      (getValues('username') || inputFocus !== 1)
-                    ? 'border-red-500 focus-visible:border-red-500'
-                    : 'border-primary',
-
+                focusedList[1] &&
+                  getInputBorderClassname(
+                    inputFocus === 1,
+                    Boolean(errors.username),
+                    getValues('username')
+                  ),
                 !isUsernameAvailable &&
                   getValues('username') &&
                   (checkedUsername === getValues('username') ||
@@ -295,18 +294,16 @@ export default function SignUpRegister() {
               type="button"
               className={cn(
                 ((isUsernameAvailable &&
-                  checkedUsername == getValues('username')) ||
+                  checkedUsername === getValues('username')) ||
                   errors.username) &&
                   'bg-gray-400',
                 'flex h-8 w-11 items-center justify-center rounded-md'
               )}
-              disabled={
+              disabled={Boolean(
                 (isUsernameAvailable &&
-                  checkedUsername == getValues('username')) ||
-                errors.username
-                  ? true
-                  : false
-              }
+                  checkedUsername === getValues('username')) ||
+                  errors.username
+              )}
               size="icon"
             >
               <Image src={checkIcon} alt="check" />
@@ -361,12 +358,12 @@ export default function SignUpRegister() {
               placeholder="Password"
               className={cn(
                 'focus-visible:ring-0',
-                !focusedList[2]
-                  ? ''
-                  : errors.password &&
-                      (getValues('password') || inputFocus !== 2)
-                    ? 'border-red-500 focus-visible:border-red-500'
-                    : 'border-primary'
+                focusedList[2] &&
+                  getInputBorderClassname(
+                    inputFocus === 2,
+                    Boolean(errors.password),
+                    getValues('password')
+                  )
               )}
               {...register('password', {
                 onChange: () => validation('password')
@@ -405,7 +402,7 @@ export default function SignUpRegister() {
             ))}
           {inputFocus !== 2 &&
             errors.password &&
-            (errors.password.message == 'Required' ? (
+            (errors.password.message === 'Required' ? (
               requiredMessage('Required')
             ) : (
               <ul className="pl-4 text-xs text-red-500">
@@ -424,12 +421,12 @@ export default function SignUpRegister() {
               })}
               className={cn(
                 'focus-visible:ring-0',
-                !focusedList[3]
-                  ? ''
-                  : errors.passwordAgain &&
-                      (getValues('passwordAgain') || inputFocus !== 3)
-                    ? 'border-red-500 focus-visible:border-red-500'
-                    : 'border-primary'
+                focusedList[3] &&
+                  getInputBorderClassname(
+                    inputFocus === 3,
+                    Boolean(errors.passwordAgain),
+                    getValues('passwordAgain')
+                  )
               )}
               placeholder="Re-enter password"
               type={passwordAgainShow ? 'text' : 'password'}
@@ -462,12 +459,12 @@ export default function SignUpRegister() {
               })}
               className={cn(
                 'focus-visible:ring-0',
-                !focusedList[4]
-                  ? ''
-                  : errors.firstName &&
-                      (getValues('firstName') || inputFocus !== 4)
-                    ? 'border-red-500 focus-visible:border-red-500'
-                    : 'border-primary'
+                focusedList[4] &&
+                  getInputBorderClassname(
+                    inputFocus === 4,
+                    Boolean(errors.firstName),
+                    getValues('firstName')
+                  )
               )}
               onFocus={() => {
                 updateFocus(4)
@@ -485,12 +482,12 @@ export default function SignUpRegister() {
               })}
               className={cn(
                 'focus-visible:ring-0',
-                !focusedList[5]
-                  ? ''
-                  : errors.lastName &&
-                      (getValues('lastName') || inputFocus !== 5)
-                    ? 'border-red-500 focus-visible:border-red-500'
-                    : 'border-primary'
+                focusedList[5] &&
+                  getInputBorderClassname(
+                    inputFocus === 5,
+                    Boolean(errors.lastName),
+                    getValues('lastName')
+                  )
               )}
               onFocus={() => {
                 updateFocus(5)
@@ -509,12 +506,12 @@ export default function SignUpRegister() {
             })}
             className={cn(
               'focus-visible:ring-0',
-              !focusedList[6]
-                ? ''
-                : errors.studentId &&
-                    (getValues('studentId') || inputFocus !== 6)
-                  ? 'border-red-500 focus-visible:border-red-500'
-                  : 'border-primary'
+              focusedList[6] &&
+                getInputBorderClassname(
+                  inputFocus === 6,
+                  Boolean(errors.studentId),
+                  getValues('studentId')
+                )
             )}
             onFocus={() => {
               updateFocus(6)
@@ -611,3 +608,17 @@ export default function SignUpRegister() {
     </div>
   )
 }
+
+const getInputBorderClassname = (
+  isFocus: boolean,
+  error: boolean,
+  value: string
+) => {
+  let className = 'border-primary'
+
+  if (error && (value || !isFocus)) {
+    className = 'border-red-500 focus-visible:border-red-500'
+  }
+
+  return className
+}
diff --git a/apps/frontend/components/auth/UpdateInformation.tsx b/apps/frontend/components/auth/UpdateInformation.tsx
index b0e3b3cba5..c5a61c8a4c 100644
--- a/apps/frontend/components/auth/UpdateInformation.tsx
+++ b/apps/frontend/components/auth/UpdateInformation.tsx
@@ -37,9 +37,8 @@ export default function UpdateInformation() {
         className="mt-8 w-full bg-red-500 font-semibold hover:bg-red-600"
         onClick={() => {
           router.push(
-            ('/settings' +
-              '?' +
-              new URLSearchParams({ updateNow: 'true' })) as Route
+            (`/settings` +
+              `?${new URLSearchParams({ updateNow: 'true' })}`) as Route
           )
         }}
       >
diff --git a/apps/frontend/components/shadcn/carousel.tsx b/apps/frontend/components/shadcn/carousel.tsx
index 5fd83511e1..f54be0169b 100644
--- a/apps/frontend/components/shadcn/carousel.tsx
+++ b/apps/frontend/components/shadcn/carousel.tsx
@@ -201,30 +201,26 @@ const CarouselPrevious = React.forwardRef<
   const { orientation, scrollPrev, canScrollPrev, canScrollNext } =
     useCarousel()
 
-  return (
-    <>
-      {(canScrollPrev || canScrollNext) && (
-        <Button
-          ref={ref}
-          variant={variant}
-          size={size}
-          className={cn(
-            'h-8 w-8',
-            orientation === 'horizontal'
-              ? '-right-12 -translate-y-1/2'
-              : '-top-12 left-1/2 -translate-x-1/2 rotate-90',
-            className
-          )}
-          disabled={!canScrollPrev}
-          onClick={scrollPrev}
-          {...props}
-        >
-          <IoIosArrowBack className="h-4 w-4" />
-          <span className="sr-only">Previous slide</span>
-        </Button>
+  return canScrollPrev || canScrollNext ? (
+    <Button
+      ref={ref}
+      variant={variant}
+      size={size}
+      className={cn(
+        'h-8 w-8',
+        orientation === 'horizontal'
+          ? '-right-12 -translate-y-1/2'
+          : '-top-12 left-1/2 -translate-x-1/2 rotate-90',
+        className
       )}
-    </>
-  )
+      disabled={!canScrollPrev}
+      onClick={scrollPrev}
+      {...props}
+    >
+      <IoIosArrowBack className="h-4 w-4" />
+      <span className="sr-only">Previous slide</span>
+    </Button>
+  ) : null
 })
 CarouselPrevious.displayName = 'CarouselPrevious'
 const CarouselNext = React.forwardRef<
@@ -234,44 +230,36 @@ const CarouselNext = React.forwardRef<
   const { orientation, scrollNext, canScrollNext, canScrollPrev } =
     useCarousel()
 
-  return (
-    <>
-      {(canScrollPrev || canScrollNext) && (
-        <Button
-          ref={ref}
-          variant={variant}
-          size={size}
-          className={cn(
-            'h-8 w-8',
-            orientation === 'horizontal'
-              ? '-right-12 top-1/2 -translate-y-1/2'
-              : '-bottom-12 left-1/2 -translate-x-1/2 rotate-90',
-            className
-          )}
-          disabled={!canScrollNext}
-          onClick={scrollNext}
-          {...props}
-        >
-          <IoIosArrowForward className="h-4 w-4" />
-          <span className="sr-only">Next slide</span>
-        </Button>
+  return canScrollPrev || canScrollNext ? (
+    <Button
+      ref={ref}
+      variant={variant}
+      size={size}
+      className={cn(
+        'h-8 w-8',
+        orientation === 'horizontal'
+          ? '-right-12 top-1/2 -translate-y-1/2'
+          : '-bottom-12 left-1/2 -translate-x-1/2 rotate-90',
+        className
       )}
-    </>
-  )
+      disabled={!canScrollNext}
+      onClick={scrollNext}
+      {...props}
+    >
+      <IoIosArrowForward className="h-4 w-4" />
+      <span className="sr-only">Next slide</span>
+    </Button>
+  ) : null
 })
 CarouselNext.displayName = 'CarouselNext'
 
 const CarouselNextGradient = () => {
   const { canScrollNext } = useCarousel()
 
-  return (
-    <>
-      {canScrollNext ? (
-        <div className="absolute bottom-[4px] right-0 h-[130px] w-[120px] self-end bg-gradient-to-r from-transparent to-white/70"></div>
-      ) : (
-        <div></div>
-      )}
-    </>
+  return canScrollNext ? (
+    <div className="absolute bottom-[4px] right-0 h-[130px] w-[120px] self-end bg-gradient-to-r from-transparent to-white/70" />
+  ) : (
+    <div />
   )
 }
 CarouselNextGradient.displayName = 'CarouselNextGradient'
@@ -279,14 +267,10 @@ CarouselNextGradient.displayName = 'CarouselNextGradient'
 const CarouselPrevGradient = () => {
   const { canScrollPrev } = useCarousel()
 
-  return (
-    <>
-      {canScrollPrev ? (
-        <div className="absolute bottom-[4px] left-0 h-[130px] w-[120px] self-start bg-gradient-to-r from-white/70 to-transparent"></div>
-      ) : (
-        <div> </div>
-      )}
-    </>
+  return canScrollPrev ? (
+    <div className="absolute bottom-[4px] left-0 h-[130px] w-[120px] self-start bg-gradient-to-r from-white/70 to-transparent" />
+  ) : (
+    <div />
   )
 }
 CarouselPrevGradient.displayName = 'CarouselPrevGradient'
diff --git a/apps/frontend/components/shadcn/date-time-picker-demo.tsx b/apps/frontend/components/shadcn/date-time-picker-demo.tsx
index 6eb424ff31..8c811a6c06 100644
--- a/apps/frontend/components/shadcn/date-time-picker-demo.tsx
+++ b/apps/frontend/components/shadcn/date-time-picker-demo.tsx
@@ -11,7 +11,7 @@ import { TimePickerDemo } from '@/components/shadcn/time-picker-demo'
 import { cn } from '@/libs/utils'
 import { format } from 'date-fns'
 import { Calendar as CalendarIcon } from 'lucide-react'
-import * as React from 'react'
+import { useEffect, useState } from 'react'
 
 export const DateTimePickerDemo = ({
   onChange,
@@ -20,16 +20,22 @@ export const DateTimePickerDemo = ({
   onChange: (date: Date) => void
   defaultValue?: Date
 }) => {
-  const [date, setDate] = React.useState<Date>()
+  const [date, setDate] = useState<Date>()
 
-  React.useEffect(() => {
+  useEffect(() => {
     if (defaultValue) {
       setDate(defaultValue)
     }
   }, [defaultValue])
 
   return (
-    <Popover onOpenChange={() => onChange(date!)}>
+    <Popover
+      onOpenChange={() => {
+        if (date) {
+          onChange(date)
+        }
+      }}
+    >
       <PopoverTrigger asChild>
         <Button
           variant={'outline'}
diff --git a/apps/frontend/components/shadcn/form.tsx b/apps/frontend/components/shadcn/form.tsx
index 0684ae0bc2..0b2039715c 100644
--- a/apps/frontend/components/shadcn/form.tsx
+++ b/apps/frontend/components/shadcn/form.tsx
@@ -109,7 +109,7 @@ const FormControl = React.forwardRef<
           ? `${formDescriptionId}`
           : `${formDescriptionId} ${formMessageId}`
       }
-      aria-invalid={!!error}
+      aria-invalid={Boolean(error)}
       {...props}
     />
   )
diff --git a/apps/frontend/components/shadcn/textarea.tsx b/apps/frontend/components/shadcn/textarea.tsx
index d61df694e0..cbdb921d3f 100644
--- a/apps/frontend/components/shadcn/textarea.tsx
+++ b/apps/frontend/components/shadcn/textarea.tsx
@@ -14,8 +14,7 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
         const end = target.selectionEnd
 
         // Insert 2 spaces at the current cursor position
-        target.value =
-          target.value.substring(0, start) + '  ' + target.value.substring(end)
+        target.value = `${target.value.substring(0, start)}  ${target.value.substring(end)}`
 
         // Move the cursor 2 characters forward
         target.selectionStart = target.selectionEnd = start + 2
diff --git a/apps/frontend/components/shadcn/time-picker-input.tsx b/apps/frontend/components/shadcn/time-picker-input.tsx
index 113dc65bf3..21a2c9748b 100644
--- a/apps/frontend/components/shadcn/time-picker-input.tsx
+++ b/apps/frontend/components/shadcn/time-picker-input.tsx
@@ -63,22 +63,32 @@ const TimePickerInput = React.forwardRef<
     )
 
     const handleKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
-      if (e.key === 'Tab') return
+      if (e.key === 'Tab') {
+        return
+      }
       e.preventDefault()
-      if (e.key === 'ArrowRight') onRightFocus?.()
-      if (e.key === 'ArrowLeft') onLeftFocus?.()
+      if (e.key === 'ArrowRight') {
+        onRightFocus?.()
+      }
+      if (e.key === 'ArrowLeft') {
+        onLeftFocus?.()
+      }
       if (['ArrowUp', 'ArrowDown'].includes(e.key)) {
         const step = e.key === 'ArrowUp' ? 1 : -1
         const newValue = getArrowByType(calculatedValue, step, picker)
-        if (flag) setFlag(false)
+        if (flag) {
+          setFlag(false)
+        }
         const tempDate = new Date(date)
         setDate(setDateByType(tempDate, newValue, picker))
       }
       if (e.key >= '0' && e.key <= '9') {
         const newValue = !flag
-          ? '0' + e.key
+          ? `0${e.key}`
           : calculatedValue.slice(1, 2) + e.key
-        if (flag) onRightFocus?.()
+        if (flag) {
+          onRightFocus?.()
+        }
         setFlag((prev) => !prev)
         const tempDate = new Date(date)
         setDate(setDateByType(tempDate, newValue, picker))
diff --git a/apps/frontend/components/shadcn/time-picker-utils.tsx b/apps/frontend/components/shadcn/time-picker-utils.tsx
index 771522cc4e..3c39ddfb3b 100644
--- a/apps/frontend/components/shadcn/time-picker-utils.tsx
+++ b/apps/frontend/components/shadcn/time-picker-utils.tsx
@@ -25,11 +25,19 @@ export const getValidNumber = (
 
   if (!isNaN(numericValue)) {
     if (!loop) {
-      if (numericValue > max) numericValue = max
-      if (numericValue < min) numericValue = min
+      if (numericValue > max) {
+        numericValue = max
+      }
+      if (numericValue < min) {
+        numericValue = min
+      }
     } else {
-      if (numericValue > max) numericValue = min
-      if (numericValue < min) numericValue = max
+      if (numericValue > max) {
+        numericValue = min
+      }
+      if (numericValue < min) {
+        numericValue = max
+      }
     }
     return numericValue.toString().padStart(2, '0')
   }
@@ -38,17 +46,23 @@ export const getValidNumber = (
 }
 
 export const getValidHour = (value: string) => {
-  if (isValidHour(value)) return value
+  if (isValidHour(value)) {
+    return value
+  }
   return getValidNumber(value, { max: 23 })
 }
 
 export const getValid12Hour = (value: string) => {
-  if (isValid12Hour(value)) return value
+  if (isValid12Hour(value)) {
+    return value
+  }
   return getValidNumber(value, { max: 12 })
 }
 
 export const getValidMinuteOrSecond = (value: string) => {
-  if (isValidMinuteOrSecond(value)) return value
+  if (isValidMinuteOrSecond(value)) {
+    return value
+  }
   return getValidNumber(value, { max: 59 })
 }
 
diff --git a/apps/frontend/libs/auth.ts b/apps/frontend/libs/auth.ts
index d9cf5b7517..d9ee4180d9 100644
--- a/apps/frontend/libs/auth.ts
+++ b/apps/frontend/libs/auth.ts
@@ -9,5 +9,5 @@ import { getClientSession } from './auth/getClientSession'
  */
 export const auth =
   typeof window === 'undefined'
-    ? async () => getServerSession(authOptions)
+    ? () => getServerSession(authOptions)
     : getClientSession()
diff --git a/apps/frontend/libs/auth/authOptions.ts b/apps/frontend/libs/auth/authOptions.ts
index bdd23b1d40..2176399d74 100644
--- a/apps/frontend/libs/auth/authOptions.ts
+++ b/apps/frontend/libs/auth/authOptions.ts
@@ -19,7 +19,7 @@ export const authOptions: NextAuthOptions = {
     maxAge: 24 * 60 * 60 // 24 hours
   },
   callbacks: {
-    jwt: async ({ token, user }: { token: JWT; user?: User }) => {
+    jwt: ({ token, user }: { token: JWT; user?: User }) => {
       if (user) {
         // When user logs in, set token. (Only when user tries to login, user will not be undefined.)
         token.username = user.username
@@ -32,7 +32,7 @@ export const authOptions: NextAuthOptions = {
 
       return token
     },
-    session: async ({ session, token }: { session: Session; token: JWT }) => {
+    session: ({ session, token }: { session: Session; token: JWT }) => {
       // When user requests session, then call jwt callback. and then call this callback.
       session.user = {
         username: token.username,
diff --git a/apps/frontend/libs/auth/getClientSession.spec.ts b/apps/frontend/libs/auth/getClientSession.spec.ts
index 88c9796ff8..578c568048 100644
--- a/apps/frontend/libs/auth/getClientSession.spec.ts
+++ b/apps/frontend/libs/auth/getClientSession.spec.ts
@@ -1,7 +1,7 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
 import { getClientSession } from './getClientSession'
 
-describe('getClientSession', async () => {
+describe('getClientSession', () => {
   const auth = getClientSession()
 
   beforeEach(() => {
diff --git a/apps/frontend/libs/auth/getJWTExpire.ts b/apps/frontend/libs/auth/getJWTExpire.ts
index 506a114994..c26c2e39ba 100644
--- a/apps/frontend/libs/auth/getJWTExpire.ts
+++ b/apps/frontend/libs/auth/getJWTExpire.ts
@@ -14,7 +14,7 @@ import { jwtDecode } from 'jwt-decode'
 export const getJWTExpire = (token: string): number => {
   const decoded = jwtDecode(token)
 
-  if (decoded.exp == null) {
+  if (decoded.exp === null || decoded.exp === undefined) {
     throw new Error('Token does not contain an expiration date')
   }
 
diff --git a/apps/frontend/libs/auth/getJWTFromResponse.spec.ts b/apps/frontend/libs/auth/getJWTFromResponse.spec.ts
index 44be870573..c5ab445276 100644
--- a/apps/frontend/libs/auth/getJWTFromResponse.spec.ts
+++ b/apps/frontend/libs/auth/getJWTFromResponse.spec.ts
@@ -7,7 +7,6 @@ describe('getJWTFromResponse', () => {
       headers: {
         authorization:
           'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMjk0Mzc3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.irmggrLtvc6EroLYv-C4MHe96mDit1R6Wbf3W-wseiA',
-        // eslint-disable-next-line @typescript-eslint/naming-convention
         'set-cookie':
           'refresh_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMzAyODM3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.BdV0hk0r_1bVIdxKyer8kzZzhSS_k4d8zvTnD28Jpy0; Max-Age=86400; Path=/api/auth/reissue; Expires=Wed, 07 Aug 2024 10:59:30 GMT; HttpOnly; Secure; SameSite=None; Secure'
       }
@@ -28,7 +27,6 @@ describe('getJWTFromResponse', () => {
   it('should throw an error if the response does not contain an access token', () => {
     const res = new Response(undefined, {
       headers: {
-        // eslint-disable-next-line @typescript-eslint/naming-convention
         'set-cookie': 'refresh_token=eyJhbGciOi...'
       }
     })
@@ -56,7 +54,6 @@ describe('getJWTFromResponse', () => {
       headers: {
         authorization:
           'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMjk0Mzc3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.irmggrLtvc6EroLYv-C4MHe96mDit1R6Wbf3W-wseiA',
-        // eslint-disable-next-line @typescript-eslint/naming-convention
         'set-cookie': 'foo=bar; Max-Age=86400;'
       }
     })
diff --git a/apps/frontend/libs/auth/getJWTFromResponse.ts b/apps/frontend/libs/auth/getJWTFromResponse.ts
index 2d2c0282a7..26edb0591f 100644
--- a/apps/frontend/libs/auth/getJWTFromResponse.ts
+++ b/apps/frontend/libs/auth/getJWTFromResponse.ts
@@ -26,11 +26,11 @@ export const getJWTFromResponse = (res: Response): JWTs => {
   const accessToken = res.headers.get('authorization')
   const cookies = res.headers.get('set-cookie')
 
-  if (accessToken == null) {
+  if (accessToken === null) {
     throw new Error('Response does not contain an access token')
   }
 
-  if (cookies == null) {
+  if (cookies === null) {
     throw new Error('Response does not contain a cookie')
   }
 
@@ -40,7 +40,7 @@ export const getJWTFromResponse = (res: Response): JWTs => {
   const refreshToken = parsedCookie.get('refresh_token')
   const refreshTokenExpires = parsedCookie.get('Expires')
 
-  if (refreshToken == null || refreshTokenExpires == null) {
+  if (refreshToken === undefined || refreshTokenExpires === undefined) {
     throw new Error(
       'Response does not contain a valid refresh token or expiration date'
     )
diff --git a/apps/frontend/libs/hooks/usePagination.ts b/apps/frontend/libs/hooks/usePagination.ts
index 47e492feec..88410ef084 100644
--- a/apps/frontend/libs/hooks/usePagination.ts
+++ b/apps/frontend/libs/hooks/usePagination.ts
@@ -99,9 +99,16 @@ export const usePagination = <T extends Item>(
       const next = Number(query.get('take')) > 0
       const full = resData.data?.length >= take
       if (full) {
-        if (next) resData.data.pop()
-        else resData.data.shift()
+        if (next) {
+          resData.data.pop()
+        } else {
+          resData.data.shift()
+        }
       }
+
+      const firstData = resData.data.at(0)
+      const lastData = resData.data.at(-1)
+
       nav.current = {
         page: {
           first: slot.current * pagesPerSlot + 1,
@@ -112,12 +119,12 @@ export const usePagination = <T extends Item>(
         },
         slot: {
           prev:
-            (next && slot.current > 0) || (!next && full)
-              ? `${baseQuery}&cursor=${resData.data.at(0)!.id}&take=${-take}`
+            ((next && slot.current > 0) || (!next && full)) && firstData
+              ? `${baseQuery}&cursor=${firstData.id}&take=${-take}`
               : '',
           next:
-            (next && full) || !next
-              ? `${baseQuery}&cursor=${resData.data.at(-1)!.id}&take=${take}`
+            ((next && full) || !next) && lastData
+              ? `${baseQuery}&cursor=${lastData.id}&take=${take}`
               : ''
         }
       }
diff --git a/apps/frontend/libs/utils.ts b/apps/frontend/libs/utils.ts
index 72ef78ff87..6d2a61b85d 100644
--- a/apps/frontend/libs/utils.ts
+++ b/apps/frontend/libs/utils.ts
@@ -35,8 +35,9 @@ export const fetcherWithAuth = fetcher.extend({
       async (request) => {
         // Add access token to request header if user is logged in.
         const session = await auth()
-        if (session)
+        if (session) {
           request.headers.set('Authorization', session.token.accessToken)
+        }
       }
     ],
     afterResponse: [
diff --git a/apps/frontend/middleware.ts b/apps/frontend/middleware.ts
index 57fc4e4320..c22e41dc02 100644
--- a/apps/frontend/middleware.ts
+++ b/apps/frontend/middleware.ts
@@ -21,7 +21,7 @@ export const middleware = async (req: NextRequest) => {
   // Handle reissue of access token
   if (token && token.accessTokenExpires <= Date.now()) {
     try {
-      const reissueRes = await fetch(baseUrl + '/auth/reissue', {
+      const reissueRes = await fetch(`${baseUrl}/auth/reissue`, {
         headers: {
           cookie: `refresh_token=${token.refreshToken}`
         },
diff --git a/apps/frontend/mocks/handlers.ts b/apps/frontend/mocks/handlers.ts
index 1c0ec5ea2e..ef26c5c264 100644
--- a/apps/frontend/mocks/handlers.ts
+++ b/apps/frontend/mocks/handlers.ts
@@ -1,7 +1,7 @@
 import { http, HttpResponse } from 'msw'
 
 export const handlers = [
-  http.get('https://test.com/api/user', async ({ request }) => {
+  http.get('https://test.com/api/user', ({ request }) => {
     const authorization = request.headers.get('Authorization')
     if (
       authorization ===
@@ -35,7 +35,7 @@ export const handlers = [
         headers: {
           authorization:
             'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMjk0Mzc3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.irmggrLtvc6EroLYv-C4MHe96mDit1R6Wbf3W-wseiA',
-          // eslint-disable-next-line @typescript-eslint/naming-convention
+
           'set-cookie':
             'refresh_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMzAyODM3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.BdV0hk0r_1bVIdxKyer8kzZzhSS_k4d8zvTnD28Jpy0; Max-Age=86400; Path=/api/auth/reissue; Expires=Wed, 07 Aug 2024 10:59:30 GMT; HttpOnly; Secure; SameSite=None; Secure'
         }
@@ -50,7 +50,7 @@ export const handlers = [
         headers: {
           authorization:
             'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMjk0Mzc3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.irmggrLtvc6EroLYv-C4MHe96mDit1R6Wbf3W-wseiAds',
-          // eslint-disable-next-line @typescript-eslint/naming-convention
+
           'set-cookie':
             'refresh_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOjIsInVzZXJuYW1lIjoiYWRtaW4iLCJpYXQiOjE3MjI5NDE5NzAsImV4cCI6MTcyMzAyODM3MCwiaXNzIjoic2trdWRpbmcuZGV2In0.BdV0hk0r_1bVIdxKyer8kzZzhSS_k4d8zvTnD28Jpy0; Max-Age=86400; Path=/api/auth/reissue; Expires=Wed, 07 Aug 2024 10:59:30 GMT; HttpOnly; Secure; SameSite=None; Secure'
         }
@@ -62,7 +62,7 @@ export const handlers = [
       })
     }
   }),
-  http.get('/next-auth/api/auth/session', async () => {
+  http.get('/next-auth/api/auth/session', () => {
     const session = {
       user: {
         username: 'admin',
diff --git a/apps/frontend/stores/editor.ts b/apps/frontend/stores/editor.ts
index 699ebc0861..d23bbb3e1e 100644
--- a/apps/frontend/stores/editor.ts
+++ b/apps/frontend/stores/editor.ts
@@ -44,7 +44,9 @@ export const getStorageKey = (
   userName: string,
   contestId?: number
 ) => {
-  if (userName === '') return undefined
+  if (userName === '') {
+    return undefined
+  }
   const problemKey = `${userName}_${problemId}${contestId ? `_${contestId}` : ''}_${language}`
   return problemKey
 }
diff --git a/apps/frontend/stores/recoverAccountModal.ts b/apps/frontend/stores/recoverAccountModal.ts
index 1164189cfd..b21ab4a79a 100644
--- a/apps/frontend/stores/recoverAccountModal.ts
+++ b/apps/frontend/stores/recoverAccountModal.ts
@@ -4,7 +4,6 @@ interface FormData {
   email: string
   verificationCode: string
   headers: {
-    /* eslint-disable-next-line @typescript-eslint/naming-convention */
     'email-auth': string
   }
 }
@@ -15,7 +14,6 @@ interface RecoverAccountModalStore {
     email: string
     verificationCode: string
     headers: {
-      /* eslint-disable-next-line @typescript-eslint/naming-convention */
       'email-auth': string
     }
   }
@@ -30,7 +28,6 @@ const useRecoverAccountModalStore = create<RecoverAccountModalStore>((set) => ({
     email: '',
     verificationCode: '',
     headers: {
-      /* eslint-disable-next-line @typescript-eslint/naming-convention */
       'email-auth': ''
     }
   },
diff --git a/apps/frontend/stores/signUpModal.ts b/apps/frontend/stores/signUpModal.ts
index f638903fca..b0b0866068 100644
--- a/apps/frontend/stores/signUpModal.ts
+++ b/apps/frontend/stores/signUpModal.ts
@@ -4,7 +4,6 @@ interface FormData {
   email: string
   verificationCode: string
   headers: {
-    /* eslint-disable-next-line @typescript-eslint/naming-convention */
     'email-auth': string
   }
 }
@@ -14,7 +13,6 @@ interface SignUpModalStore {
     email: string
     verificationCode: string
     headers: {
-      /* eslint-disable-next-line @typescript-eslint/naming-convention */
       'email-auth': string
     }
   }
@@ -29,7 +27,6 @@ const useSignUpModalStore = create<SignUpModalStore>((set) => ({
     email: '',
     verificationCode: '',
     headers: {
-      /* eslint-disable-next-line @typescript-eslint/naming-convention */
       'email-auth': ''
     }
   },
diff --git a/apps/frontend/types/type.ts b/apps/frontend/types/type.ts
index 805594808c..cdca547291 100644
--- a/apps/frontend/types/type.ts
+++ b/apps/frontend/types/type.ts
@@ -52,7 +52,7 @@ export interface ContestProblem {
   difficulty: Level
   order: number
   submissionCount: number
-  maxScore: number
+  maxScore: number | null
   score: string | null
   submissionTime: string | null
   acceptedRate: number
diff --git a/eslint.config.mjs b/eslint.config.mjs
index abab3983ae..a1bb1b5002 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -56,8 +56,11 @@ export default eslintTS.config(
       '@typescript-eslint/no-import-type-side-effects': 'error'
     }
   },
+
+  /* Backend configuration */
+
   {
-    files: ['**/*.ts'],
+    files: ['apps/backend/**/*.ts'],
     rules: {
       '@typescript-eslint/naming-convention': [
         'error',
@@ -88,8 +91,6 @@ export default eslintTS.config(
       ]
     }
   },
-
-  /* Backend configuration */
   {
     files: ['apps/backend/**/*'],
     rules: {
@@ -141,6 +142,14 @@ export default eslintTS.config(
         'error',
         path.join(__dirname, 'apps/frontend/app')
       ],
+      eqeqeq: ['error', 'always'],
+      curly: 'error',
+      'prefer-template': 'error',
+      'prefer-const': 'error',
+      'no-unneeded-ternary': 'error',
+      'no-nested-ternary': 'error',
+      'require-await': 'error',
+      'no-implicit-coercion': 'error',
       'no-restricted-imports': [
         'error',
         {
@@ -157,6 +166,8 @@ export default eslintTS.config(
           message: 'Please use @generated/graphql instead.'
         }
       ],
+      '@typescript-eslint/no-non-null-assertion': 'error',
+      '@typescript-eslint/no-unnecessary-type-assertion': 'error',
       '@typescript-eslint/no-empty-object-type': [
         'error',
         { allowInterfaces: 'with-single-extends' }
@@ -164,6 +175,28 @@ export default eslintTS.config(
       '@typescript-eslint/no-unused-expressions': [
         'error',
         { allowShortCircuit: true, allowTernary: true }
+      ],
+      'react/jsx-no-useless-fragment': 'error',
+      'react/self-closing-comp': 'error'
+    }
+  },
+  {
+    files: ['apps/frontend/**/*.ts?(x)'],
+    rules: {
+      '@typescript-eslint/naming-convention': [
+        'error',
+        {
+          selector: ['import', 'function'],
+          format: ['camelCase', 'PascalCase']
+        },
+        {
+          selector: 'typeLike',
+          format: ['PascalCase']
+        },
+        {
+          selector: 'variable',
+          format: ['camelCase', 'UPPER_CASE', 'PascalCase']
+        }
       ]
     }
   },