diff --git a/src/constants/errors.ts b/src/constants/errors.ts
new file mode 100644
index 0000000000..3004188572
--- /dev/null
+++ b/src/constants/errors.ts
@@ -0,0 +1,11 @@
+import { FetchBaseQueryMeta } from '@reduxjs/toolkit/dist/query'
+import { captureException } from '@sentry/react'
+
+export class ApiValidateError extends Error {
+  constructor(res: any, meta: FetchBaseQueryMeta | undefined) {
+    super('Data error. Please try again later.')
+    const e = new Error(`[API validate fail] ${meta?.request.url}`)
+    e.name = 'APIValidateFail'
+    captureException(e, { level: 'error', extra: { res, meta } })
+  }
+}
diff --git a/src/services/blackjack.ts b/src/services/blackjack.ts
index df8333139e..57eaa4b84f 100644
--- a/src/services/blackjack.ts
+++ b/src/services/blackjack.ts
@@ -1,18 +1,20 @@
 import { createApi, fetchBaseQuery } from '@reduxjs/toolkit/query/react'
 
 import { BLACKJACK_API } from 'constants/env'
+import { ApiValidateError } from 'constants/errors'
+import { isArray, isBoolean, isNumber, isString, isStruct } from 'utils/validate'
 
-type BlackjackCheck = {
-  blacklisted: boolean
-  expiryMs: string
-  reason: number
-}
-
-type BlackjackResponse = {
-  data: {
-    wallets: BlackjackCheck[]
-  }
-}
+const verifyBlackjackResponse = isStruct({
+  data: isStruct({
+    wallets: isArray(
+      isStruct({
+        blacklisted: isBoolean,
+        updatedMs: isString,
+        reason: isNumber,
+      }),
+    ),
+  }),
+})
 
 const blackjackApi = createApi({
   reducerPath: 'blackjackApi',
@@ -20,15 +22,18 @@ const blackjackApi = createApi({
     baseUrl: `${BLACKJACK_API}/v1`,
   }),
   endpoints: builder => ({
-    checkBlackjack: builder.query<BlackjackCheck, string>({
+    checkBlackjack: builder.query({
       query: (address: string) => ({
         url: '/check',
         params: {
           wallets: address,
         },
       }),
-      transformResponse: (res: BlackjackResponse): BlackjackCheck => {
-        return res.data.wallets[0]
+      transformResponse: (res: unknown, meta) => {
+        if (verifyBlackjackResponse(res)) {
+          return res.data.wallets[0]
+        }
+        throw new ApiValidateError(res, meta)
       },
     }),
   }),
diff --git a/src/utils/validate.ts b/src/utils/validate.ts
new file mode 100644
index 0000000000..990f9d86eb
--- /dev/null
+++ b/src/utils/validate.ts
@@ -0,0 +1,103 @@
+/* eslint-disable @typescript-eslint/ban-ts-comment */
+
+type GuardedType<T> = T extends (x: any) => x is infer U ? U : never
+
+function isNull(input: unknown): input is null | undefined {
+  if (input === undefined) return true
+  if (input === null) return true
+  return false
+}
+export function isNumber(input: unknown): input is number {
+  return typeof input === 'number'
+}
+
+export function isBoolean(input: unknown | any): input is boolean {
+  return typeof input === 'boolean'
+}
+
+export function isString(input: unknown): input is string {
+  return typeof input === 'string'
+}
+
+// @ts-ignore
+export function isArray<T extends VerifierTypes>(elementVerifier: T): (input: unknown) => input is GuardedType<T>[] {
+  return (input: unknown): input is GuardedType<T>[] => {
+    if (!Array.isArray(input)) return false
+    // @ts-ignore
+    return input.every(elementVerifier)
+  }
+}
+
+export function isStruct<T extends { [key: string]: VerifierTypes }, U extends keyof T>(
+  struct: T,
+): (input: unknown) => input is { readonly [keys in U]: GuardedType<T[keys]> } {
+  const verifiers = Object.entries(struct)
+
+  return (input: unknown): input is { [keys in U]: GuardedType<T[keys]> } => {
+    if (typeof input !== 'object') return false
+    if (isNull(input)) return false
+    return verifiers.every(([key, verify]) => verify((input as Record<string, any>)[key]))
+  }
+}
+
+// @ts-ignore
+type VerifierTypes =
+  | typeof isString
+  | typeof isNumber
+  | typeof isBoolean
+  | ReturnType<typeof isArray>
+  | ReturnType<typeof isStruct>
+
+/**
+ * Use for fields that acceptable to be `undefined` or `null`
+ *
+ * Do not use this for fields expected to be non-null to be run correctly, e.g: `response.data`
+ *
+ * If you are using nesting, it's likely you've used it incorrectly.
+ */
+export function isNullable<T extends VerifierTypes>(
+  verifier: T,
+): (input: unknown) => input is null | undefined | GuardedType<T> {
+  return (input: unknown): input is null | undefined | GuardedType<T> => {
+    if (input === undefined) return true
+    if (input === null) return true
+    return verifier(input)
+  }
+}
+
+/* eslint-disable @typescript-eslint/no-unused-vars */
+const ValidateBalanceExample = isArray(
+  isStruct({
+    result: isNullable(isArray(isString)),
+  }),
+)
+const ValidateComplexResponseExample = isStruct({
+  data: isStruct({
+    wallets: isArray(
+      isStruct({
+        address: isString,
+        ens: isNullable(isString),
+        ETH: isNumber,
+        reward: isNullable(isNumber),
+        txs: isArray(isStruct({ id: isString })),
+        balances: isNullable(ValidateBalanceExample),
+      }),
+    ),
+    pagination: isStruct({
+      pagination: isNumber,
+      totalItems: isNumber,
+    }),
+  }),
+})
+type ExtractedBalances = GuardedType<typeof ValidateBalanceExample>
+
+let complexResponseExample: any
+if (ValidateComplexResponseExample(complexResponseExample)) {
+  // `complexResponseExample` has been generated type now. You can try:
+  type Wallets = typeof complexResponseExample.data.wallets
+  const balance: ExtractedBalances | null | undefined = complexResponseExample.data.wallets[0].balances
+} else {
+  // complexResponseExample is unknown type
+  complexResponseExample
+}
+/* eslint-enable @typescript-eslint/no-unused-vars */