diff --git a/core/invertGraph.ts b/core/invertGraph.ts
new file mode 100644
index 0000000..d5daff5
--- /dev/null
+++ b/core/invertGraph.ts
@@ -0,0 +1,72 @@
+import { CategoryName } from './types/Category'
+import { Person, PersonList } from './types/Person'
+import mappings from './invertedMappings.json'
+
+type InvertedPerson = {
+  id: string
+  name: string
+  available: boolean
+  relation: string
+  relatedTo: string
+}
+
+type InvertedPersonList = Record<string, InvertedPerson>
+
+export function defaultRoot(): Person {
+  return {
+    id: '0',
+    name: 'Defunto',
+    available: false,
+    degree: 0,
+    root: null,
+    category: 'children',
+    relatives: [],
+  }
+}
+
+export function invertGraph(root: Person, list: InvertedPersonList): PersonList {
+  const personList: PersonList = { '0': root }
+  for (const person of Object.values(list)) {
+    const degree = relationIdToDegree(person.relation)
+    const category = relationIdToCategory(person.relation)
+    const root = person.relatedTo === '' ? '0' : person.relatedTo
+
+    personList[person.id] = {
+      id: person.id,
+      name: person.name,
+      available: person.available,
+      degree,
+      root,
+      category,
+      relatives: [],
+    }
+  }
+
+  for (const person of Object.values(personList)) {
+    if (!person.root) {
+      continue
+    }
+
+    personList[person.root].relatives.push(person.id)
+  }
+
+  return personList
+}
+
+function relationIdToDegree(relation: string): number {
+  const mapping = mappings[relation as keyof typeof mappings]
+  if (!mapping) {
+    throw new Error('Unknown relation')
+  }
+
+  return mapping.degree
+}
+
+function relationIdToCategory(relation: string): CategoryName {
+  const mapping = mappings[relation as keyof typeof mappings]
+  if (!mapping) {
+    throw new Error('Unknown relation')
+  }
+
+  return mapping.category as CategoryName
+}
diff --git a/core/invertedMappings.json b/core/invertedMappings.json
new file mode 100644
index 0000000..695ec15
--- /dev/null
+++ b/core/invertedMappings.json
@@ -0,0 +1,22 @@
+{
+  "figlio": { "category": "children", "degree": 1 },
+  "nipote in linea retta": { "category": "children", "degree": 2 },
+  "pronipote in linea retta": { "category": "children", "degree": 3 },
+  "abnipote in linea retta": { "category": "children", "degree": 4 },
+  "genitore": { "category": "ascendants", "degree": 1 },
+  "fratello": { "category": "bilinear", "degree": 2 },
+  "nipote in linea collaterale": { "category": "children", "degree": 3 },
+  "pronipote in linea collaterale": { "category": "children", "degree": 4 },
+  "abnipote in linea collaterale": { "category": "children", "degree": 5 },
+  "zio": { "category": "others", "degree": 3 },
+  "cugino": { "category": "children", "degree": 4 },
+  "figlio di cugino": { "category": "children", "degree": 5 },
+  "nipote di cugino": { "category": "children", "degree": 6 },
+  "nonno": { "category": "ascendants", "degree": 2 },
+  "prozio": { "category": "others", "degree": 4 },
+  "secondo cugino": { "category": "children", "degree": 5 },
+  "figlio di secondo cugino": { "category": "children", "degree": 6 },
+  "bisavo": { "category": "ascendants", "degree": 3 },
+  "trisavo": { "category": "children", "degree": 4 },
+  "coniuge": { "category": "spouse", "degree": 1 }
+}
diff --git a/package-lock.json b/package-lock.json
index 83ea1ea..0403ecb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2652,9 +2652,9 @@
       }
     },
     "node_modules/caniuse-lite": {
-      "version": "1.0.30001427",
-      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001427.tgz",
-      "integrity": "sha512-lfXQ73oB9c8DP5Suxaszm+Ta2sr/4tf8+381GkIm1MLj/YdLf+rEDyDSRCzeltuyTVGm+/s18gdZ0q+Wmp8VsQ==",
+      "version": "1.0.30001584",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001584.tgz",
+      "integrity": "sha512-LOz7CCQ9M1G7OjJOF9/mzmqmj3jE/7VOmrfw6Mgs0E8cjOsbRXQJHsPBfmBOXDskXKrHLyyW3n7kpDW/4BsfpQ==",
       "funding": [
         {
           "type": "opencollective",
@@ -2663,6 +2663,10 @@
         {
           "type": "tidelift",
           "url": "https://tidelift.com/funding/github/npm/caniuse-lite"
+        },
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
         }
       ]
     },
@@ -9477,9 +9481,9 @@
       "dev": true
     },
     "caniuse-lite": {
-      "version": "1.0.30001427",
-      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001427.tgz",
-      "integrity": "sha512-lfXQ73oB9c8DP5Suxaszm+Ta2sr/4tf8+381GkIm1MLj/YdLf+rEDyDSRCzeltuyTVGm+/s18gdZ0q+Wmp8VsQ=="
+      "version": "1.0.30001584",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001584.tgz",
+      "integrity": "sha512-LOz7CCQ9M1G7OjJOF9/mzmqmj3jE/7VOmrfw6Mgs0E8cjOsbRXQJHsPBfmBOXDskXKrHLyyW3n7kpDW/4BsfpQ=="
     },
     "chalk": {
       "version": "4.1.2",
diff --git a/pages/api/health.ts b/pages/api/health.ts
new file mode 100644
index 0000000..4642b0a
--- /dev/null
+++ b/pages/api/health.ts
@@ -0,0 +1,5 @@
+import { NextApiRequest, NextApiResponse } from 'next'
+
+export default function handler(req: NextApiRequest, res: NextApiResponse) {
+  return res.status(200).send('Hello')
+}
diff --git a/pages/api/inheritance.ts b/pages/api/inheritance.ts
index f7be1c0..fcf6330 100644
--- a/pages/api/inheritance.ts
+++ b/pages/api/inheritance.ts
@@ -2,9 +2,14 @@ import { NextApiRequest, NextApiResponse } from 'next'
 import { calculateInheritance } from '../../core/inheritance'
 
 export default function handler(req: NextApiRequest, res: NextApiResponse) {
-  if (req.method !== 'POST') return res.status(405).send({ error: 'Method not allowed' })
-  if (req.headers['content-type'] !== 'application/json')
+  if (req.method !== 'POST') {
+    return res.status(405).send({ error: 'Method not allowed' })
+  }
+  if (req.headers['content-type'] !== 'application/json') {
     return res.status(400).send({ error: 'Content type not allowed' })
+  }
+
+  // TODO: Don't require sender to set back pointers for people, only the relatives array
 
   try {
     const result = calculateInheritance(req.body)
diff --git a/pages/api/inverted/inheritance.ts b/pages/api/inverted/inheritance.ts
new file mode 100644
index 0000000..fcb7798
--- /dev/null
+++ b/pages/api/inverted/inheritance.ts
@@ -0,0 +1,21 @@
+import { NextApiRequest, NextApiResponse } from 'next'
+import { calculateInheritance } from '../../../core/inheritance'
+import { defaultRoot, invertGraph } from '../../../core/invertGraph'
+
+export default function handler(req: NextApiRequest, res: NextApiResponse) {
+  if (req.method !== 'POST') {
+    return res.status(405).send({ error: 'Method not allowed' })
+  }
+
+  if (req.headers['content-type'] !== 'application/json') {
+    return res.status(400).send({ error: 'Content type not allowed' })
+  }
+
+  try {
+    const graph = invertGraph(defaultRoot(), req.body)
+    const result = calculateInheritance(graph)
+    return res.json(result)
+  } catch (error) {
+    return res.status(500).send({ error: 'Failed to parse body' })
+  }
+}