diff --git a/api-gateway/eslint.config.mjs b/api-gateway/eslint.config.mjs
new file mode 100644
index 0000000..d8e4eb8
--- /dev/null
+++ b/api-gateway/eslint.config.mjs
@@ -0,0 +1,79 @@
+// SPDX-FileCopyrightText: 2017-2024 City of Espoo
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+import eslint from '@eslint/js'
+import tsParser from '@typescript-eslint/parser'
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended'
+import globals from 'globals'
+import typescriptEslint from 'typescript-eslint'
+
+export default [
+  { ignores: ['.yarn', 'dist', 'eslint.config.mjs'] },
+  eslint.configs.recommended,
+  ...typescriptEslint.configs.recommended,
+  ...typescriptEslint.configs.stylisticTypeChecked,
+  {
+    languageOptions: {
+      parser: tsParser,
+      ecmaVersion: 2018,
+      sourceType: 'module',
+      parserOptions: {
+        projectService: true,
+        project: './tsconfig.json',
+        tsconfigRootDir: import.meta.dirname,
+        globals: globals.node,
+        ecmaFeatures: {
+          modules: true
+        }
+      }
+    }
+  },
+  {
+    files: ['**/*.ts'],
+    rules: {
+      '@typescript-eslint/no-unused-vars': [
+        'warn',
+        {
+          args: 'all',
+          argsIgnorePattern: '^_',
+          caughtErrors: 'all',
+          caughtErrorsIgnorePattern: '^.*',
+          destructuredArrayIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          ignoreRestSiblings: true
+        }
+      ]
+    }
+  },
+  {
+    files: ['**/*.{ts,js,mjs}'],
+    rules: {
+      '@typescript-eslint/consistent-type-definitions': 'off',
+      '@typescript-eslint/no-empty-object-type': [
+        'error',
+        { allowInterfaces: 'always' }
+      ],
+      '@typescript-eslint/no-misused-promises': [
+        'error',
+        { checksVoidReturn: false }
+      ],
+      '@typescript-eslint/prefer-nullish-coalescing': 'off',
+      '@typescript-eslint/prefer-optional-chain': 'off',
+      '@typescript-eslint/prefer-promise-reject-errors': 'off'
+    }
+  },
+  {
+    files: ['**/*.{js,mjs}'],
+    rules: {
+      '@typescript-eslint/no-var-requires': 'off'
+    }
+  },
+  {
+    files: ['**/*.js'],
+    rules: {
+      '@typescript-eslint/no-require-imports': 'off'
+    }
+  },
+  eslintPluginPrettierRecommended
+]
diff --git a/api-gateway/package.json b/api-gateway/package.json
index d4cbde2..8fe9a5a 100644
--- a/api-gateway/package.json
+++ b/api-gateway/package.json
@@ -7,7 +7,7 @@
   "scripts": {
     "clean": "rm -rf ./build ./dist",
     "build": "yarn clean && yarn install && tsc --build .",
-    "lint": "eslint --ext .ts,.tsx --max-warnings 0 .",
+    "lint": "eslint --max-warnings 0 .",
     "dev": "tsc --build . && concurrently --prefix '[{name}]' --names 'tsc,nodemon' 'tsc --build --preserveWatchOutput -w .' 'NODE_ENV=local nodemon dist/index.js'"
   },
   "dependencies": {
@@ -57,7 +57,8 @@
     "nodemon": "^3.1.7",
     "prettier": "^3.3.3",
     "ts-node": "^10.9.2",
-    "typescript": "^5.7.2"
+    "typescript": "^5.7.2",
+    "typescript-eslint": "^8.16.0"
   },
   "resolutions": {
     "@types/mime": "3.0.4"
@@ -69,35 +70,6 @@
     "singleQuote": true,
     "trailingComma": "none"
   },
-  "eslintConfig": {
-    "extends": [
-      "eslint:recommended",
-      "plugin:@typescript-eslint/recommended",
-      "plugin:@typescript-eslint/stylistic",
-      "plugin:prettier/recommended"
-    ],
-    "parser": "@typescript-eslint/parser",
-    "parserOptions": {
-      "ecmaVersion": 2018,
-      "sourceType": "module",
-      "project": "./tsconfig.json",
-      "ecmaFeatures": {
-        "modules": true
-      }
-    },
-    "plugins": [
-      "@typescript-eslint"
-    ],
-    "rules": {
-      "@typescript-eslint/no-unused-vars": [
-        "warn",
-        {
-          "argsIgnorePattern": "^_",
-          "varsIgnorePattern": "^_"
-        }
-      ]
-    }
-  },
   "engines": {
     "node": ">= 20.11.0"
   },
diff --git a/api-gateway/src/auth/saml/index.ts b/api-gateway/src/auth/saml/index.ts
index 051ddf7..eef8e5e 100644
--- a/api-gateway/src/auth/saml/index.ts
+++ b/api-gateway/src/auth/saml/index.ts
@@ -108,7 +108,7 @@ export function createAdSamlStrategy(
     }
   }
 
-  const loginVerify: VerifyWithRequest = (req, profile, done) => {
+  const loginVerify: VerifyWithRequest = (_req, profile, done) => {
     if (!profile) return done(null, undefined)
     const parseResult = Profile.safeParse(profile)
     if (!parseResult.success) {
diff --git a/api-gateway/src/clients/service-client.ts b/api-gateway/src/clients/service-client.ts
index bb4156e..5d2a33d 100644
--- a/api-gateway/src/clients/service-client.ts
+++ b/api-gateway/src/clients/service-client.ts
@@ -2,9 +2,10 @@
 //
 // SPDX-License-Identifier: LGPL-2.1-or-later
 
-import express from 'express'
 import axios from 'axios'
-import { createAuthHeader, AppSessionUser } from '../auth/index.js'
+import express from 'express'
+
+import { AppSessionUser, createAuthHeader } from '../auth/index.js'
 import { serviceUrl } from '../config.js'
 
 export const client = axios.create({
@@ -17,7 +18,9 @@ const systemUser: AppSessionUser = {
 
 export type ServiceRequestHeader = 'Authorization' | 'X-Request-ID'
 
-export type ServiceRequestHeaders = { [H in ServiceRequestHeader]?: string }
+export type ServiceRequestHeaders = Partial<
+  Record<ServiceRequestHeader, string>
+>
 
 export function createServiceRequestHeaders(
   req: express.Request | undefined,
diff --git a/api-gateway/src/logging/index.ts b/api-gateway/src/logging/index.ts
index fcc5282..cf575db 100644
--- a/api-gateway/src/logging/index.ts
+++ b/api-gateway/src/logging/index.ts
@@ -76,7 +76,7 @@ export const logDebug: LogFn = (msg, req?, meta?) =>
 function log(
   level: LogLevel,
   msg: string,
-  req?: Request,
+  _req?: Request,
   meta?: LogMeta,
   err?: Error
 ): void {
diff --git a/api-gateway/src/utils/express.ts b/api-gateway/src/utils/express.ts
index b1d2c26..87631b7 100644
--- a/api-gateway/src/utils/express.ts
+++ b/api-gateway/src/utils/express.ts
@@ -65,7 +65,6 @@ declare global {
       spanId?: string
       samlLogoutRequest: passportSaml.Profile
     }
-    // eslint-disable-next-line @typescript-eslint/no-empty-interface
     interface User extends AppSessionUser {}
   }
 }
@@ -80,7 +79,7 @@ declare global {
 // * `req.secure`: is original request https (true)
 export function trustReverseProxy(app: express.Application) {
   app.set('trust proxy', 3) // private ALB, proxy nginx, public ALB
-  app.use((req, res, next) => {
+  app.use((req, _res, next) => {
     if ('x-original-forwarded-proto' in req.headers) {
       req.headers['x-forwarded-proto'] =
         req.headers['x-original-forwarded-proto']
diff --git a/api-gateway/src/utils/promise-utils.ts b/api-gateway/src/utils/promise-utils.ts
index 34f8919..9a1d867 100644
--- a/api-gateway/src/utils/promise-utils.ts
+++ b/api-gateway/src/utils/promise-utils.ts
@@ -8,7 +8,6 @@ export function fromCallback<T>(
   f: (cb: (err: any, result?: T) => void) => void
 ): Promise<T> {
   return new Promise<T>((resolve, reject) =>
-    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     f((err, result) => (err ? reject(err) : resolve(result!)))
   )
 }
diff --git a/api-gateway/yarn.lock b/api-gateway/yarn.lock
index 4f56e46..7972e02 100644
--- a/api-gateway/yarn.lock
+++ b/api-gateway/yarn.lock
@@ -653,6 +653,29 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/eslint-plugin@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/eslint-plugin@npm:8.16.0"
+  dependencies:
+    "@eslint-community/regexpp": "npm:^4.10.0"
+    "@typescript-eslint/scope-manager": "npm:8.16.0"
+    "@typescript-eslint/type-utils": "npm:8.16.0"
+    "@typescript-eslint/utils": "npm:8.16.0"
+    "@typescript-eslint/visitor-keys": "npm:8.16.0"
+    graphemer: "npm:^1.4.0"
+    ignore: "npm:^5.3.1"
+    natural-compare: "npm:^1.4.0"
+    ts-api-utils: "npm:^1.3.0"
+  peerDependencies:
+    "@typescript-eslint/parser": ^8.0.0 || ^8.0.0-alpha.0
+    eslint: ^8.57.0 || ^9.0.0
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: aa3d551d4f09940eee0c08328cb0db3a2391a8bba6d044f6bb38c51ac864896519c647d4b8fd99f7c094cc677bcf22454b27322014a08b2f2fb25695a43820db
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/eslint-plugin@npm:^8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/eslint-plugin@npm:8.15.0"
@@ -676,6 +699,24 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/parser@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/parser@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/scope-manager": "npm:8.16.0"
+    "@typescript-eslint/types": "npm:8.16.0"
+    "@typescript-eslint/typescript-estree": "npm:8.16.0"
+    "@typescript-eslint/visitor-keys": "npm:8.16.0"
+    debug: "npm:^4.3.4"
+  peerDependencies:
+    eslint: ^8.57.0 || ^9.0.0
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: ac1e2bfdbfe212da470bb17915b5228f7a6b027332b05eb8bcbbad440a81b2476c649e54e232084838e1edc005e6d7dc7a44899587d73672dd3d5484d9dbf9f8
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/parser@npm:^8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/parser@npm:8.15.0"
@@ -704,6 +745,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/scope-manager@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/scope-manager@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/types": "npm:8.16.0"
+    "@typescript-eslint/visitor-keys": "npm:8.16.0"
+  checksum: e0aea61f248b39049d4ce21c19f9c8af1a8024f4f92abc8c1d5b79ea65b013c6c4ff41efb92995050036aa95b6a705601917b56809d9ec1fbbab387054aeb269
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/type-utils@npm:8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/type-utils@npm:8.15.0"
@@ -721,6 +772,23 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/type-utils@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/type-utils@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/typescript-estree": "npm:8.16.0"
+    "@typescript-eslint/utils": "npm:8.16.0"
+    debug: "npm:^4.3.4"
+    ts-api-utils: "npm:^1.3.0"
+  peerDependencies:
+    eslint: ^8.57.0 || ^9.0.0
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: b91f6cef6af7e4f82a1dba9622d5ec9f46d1983eecfb88a1adbd310c7f980fedf5c8a198bfe968aae59fc386e4c437f55a7533988252eb9cbb0bdac8321e3dba
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/types@npm:8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/types@npm:8.15.0"
@@ -728,6 +796,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/types@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/types@npm:8.16.0"
+  checksum: b37b26cd0e45b0cd6f7d492a07af583e4877d798495ab5fc1cfacb3c561b6d7981e3166f0475bb997e6c6d56ef903e160895174c7e63c08322dbb42d026cf7dc
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/typescript-estree@npm:8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/typescript-estree@npm:8.15.0"
@@ -747,6 +822,25 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/typescript-estree@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/typescript-estree@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/types": "npm:8.16.0"
+    "@typescript-eslint/visitor-keys": "npm:8.16.0"
+    debug: "npm:^4.3.4"
+    fast-glob: "npm:^3.3.2"
+    is-glob: "npm:^4.0.3"
+    minimatch: "npm:^9.0.4"
+    semver: "npm:^7.6.0"
+    ts-api-utils: "npm:^1.3.0"
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: 823cf55d331cf7283547a2860a5d7bfd7dbd497be6e87b226dd7456b36db214de1504855afbbaef8d89932c11a1e589d4cb2a4093b6f1c542a4ce8319d988006
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/utils@npm:8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/utils@npm:8.15.0"
@@ -764,6 +858,23 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/utils@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/utils@npm:8.16.0"
+  dependencies:
+    "@eslint-community/eslint-utils": "npm:^4.4.0"
+    "@typescript-eslint/scope-manager": "npm:8.16.0"
+    "@typescript-eslint/types": "npm:8.16.0"
+    "@typescript-eslint/typescript-estree": "npm:8.16.0"
+  peerDependencies:
+    eslint: ^8.57.0 || ^9.0.0
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: 80ba35b97a8e80ac2b54a56ac041b4f4583328d764e1693e7d3750de383cbcefcb7e838b75e550e8aa4df446f4b41460da6dc83543517280a4e3a61546c1a8dc
+  languageName: node
+  linkType: hard
+
 "@typescript-eslint/visitor-keys@npm:8.15.0":
   version: 8.15.0
   resolution: "@typescript-eslint/visitor-keys@npm:8.15.0"
@@ -774,6 +885,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@typescript-eslint/visitor-keys@npm:8.16.0":
+  version: 8.16.0
+  resolution: "@typescript-eslint/visitor-keys@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/types": "npm:8.16.0"
+    eslint-visitor-keys: "npm:^4.2.0"
+  checksum: e3f231a3e8ca2f7a3dc0e9ebdc3ea1f51a377b1285727413b4c89c44dbfaf342f2574b1b4e7f478f295963045a6058e27b4827816fe2a5a2d09f565eb68522c7
+  languageName: node
+  linkType: hard
+
 "@xmldom/is-dom-node@npm:^1.0.1":
   version: 1.0.1
   resolution: "@xmldom/is-dom-node@npm:1.0.1"
@@ -3038,6 +3159,7 @@ __metadata:
     source-map-support: "npm:^0.5.21"
     ts-node: "npm:^10.9.2"
     typescript: "npm:^5.7.2"
+    typescript-eslint: "npm:^8.16.0"
     zod: "npm:^3.23.8"
   languageName: unknown
   linkType: soft
@@ -4043,6 +4165,22 @@ __metadata:
   languageName: node
   linkType: hard
 
+"typescript-eslint@npm:^8.16.0":
+  version: 8.16.0
+  resolution: "typescript-eslint@npm:8.16.0"
+  dependencies:
+    "@typescript-eslint/eslint-plugin": "npm:8.16.0"
+    "@typescript-eslint/parser": "npm:8.16.0"
+    "@typescript-eslint/utils": "npm:8.16.0"
+  peerDependencies:
+    eslint: ^8.57.0 || ^9.0.0
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: bbcb31482210aeb715c0f41f659d642491828c0779426e5cceef70fa0ad96f3eeaf0cd3faaed1cc50965855a5324cf0b03790abc284f5364b2be458b0380337a
+  languageName: node
+  linkType: hard
+
 "typescript@npm:^5.7.2":
   version: 5.7.2
   resolution: "typescript@npm:5.7.2"