diff --git a/.flowconfig b/.flowconfig
new file mode 100644
index 0000000000..c0f278dccd
--- /dev/null
+++ b/.flowconfig
@@ -0,0 +1,30 @@
+[ignore]
+.*/node_modules/.*
+.*/build/.*
+.*/public/.*
+.*/lib/.*
+.*/coverage/.*
+.*/tests/.*
+.*/types/.*
+.*/logs/.*
+.*/install/.*
+.*/loader.js
+.*/require-main.js
+.*/webpack.installer.js
+.*/commitlint.config.js
+.*/app.js
+.*/Gruntfile.js
+
+[include]
+./src
+
+[libs]
+
+[lints]
+untyped-type-import=error
+internal-type=error
+deprecated-type-bool=error
+
+[options]
+
+[strict]
diff --git a/.github/workflows/flow-check.yml b/.github/workflows/flow-check.yml
new file mode 100644
index 0000000000..29eccf498d
--- /dev/null
+++ b/.github/workflows/flow-check.yml
@@ -0,0 +1,81 @@
+name: Flow Tests
+
+on:
+  pull_request:
+    branches:
+      - f24
+  workflow_call: # Usually called from deploy
+
+defaults:
+  run:
+    shell: bash
+
+permissions:
+  checks: write  # for coverallsapp/github-action to create new checks
+  contents: read  # for actions/checkout to fetch code
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    env:
+      TEST_ENV: 'production'
+
+    services:
+      redis:
+        image: 'redis:7.2.4'
+        # Set health checks to wait until redis has started
+        options: >-
+          --health-cmd "redis-cli ping"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          # Maps port 6379 on service container to the host
+          - 6379:6379
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - run: cp install/package.json package.json
+
+      - name: Install Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: NPM Install
+        uses: bahmutov/npm-install@v1
+        with:
+          useLockFile: false
+
+      - name: Setup for Redis
+        env:
+          SETUP: >-
+            {
+              "url": "http://127.0.0.1:4567/forum",
+              "secret": "abcdef",
+              "admin:username": "admin",
+              "admin:email": "test@example.org",
+              "admin:password": "hAN3Eg8W",
+              "admin:password:confirm": "hAN3Eg8W",
+
+              "database": "redis",
+              "redis:host": "127.0.0.1",
+              "redis:port": 6379,
+              "redis:password": "",
+              "redis:database": 0
+            }
+          CI: >-
+            {
+              "host": "127.0.0.1",
+              "database": 1,
+              "port": 6379
+            }
+        run: |
+          node app --setup="${SETUP}" --ci="${CI}"
+
+      - name: Install Flow
+        run: npm install --save-dev flow-bin
+
+      - name: Run Flow
+        run: npx flow check --all
diff --git a/flow-output.txt b/flow-output.txt
new file mode 100644
index 0000000000..741acab0d8
--- /dev/null
+++ b/flow-output.txt
@@ -0,0 +1,506 @@
+Error ----------------------------------------------------------------------------------------- src/admin/search.js:5:30
+
+Cannot resolve module `sanitize-html`. [cannot-resolve-module]
+
+   5| const sanitizeHTML = require('sanitize-html');
+                                   ^^^^^^^^^^^^^^^
+
+
+Error ----------------------------------------------------------------------------------------- src/admin/search.js:6:23
+
+Cannot resolve module `nconf`. [cannot-resolve-module]
+
+   6| const nconf = require('nconf');
+                            ^^^^^^^
+
+
+Error ----------------------------------------------------------------------------------------- src/admin/search.js:7:25
+
+Cannot resolve module `winston`. [cannot-resolve-module]
+
+   7| const winston = require('winston');
+                              ^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:12:28
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at identifier: [signature-verification-failure]
+
+   12| function filterDirectories(directories) {
+                                  ^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:12:28
+
+Missing an annotation on `directories`. [missing-local-annot]
+
+   12| function filterDirectories(directories) {
+                                  ^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:12:40
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at function return: [signature-verification-failure]
+
+   12| function filterDirectories(directories) {
+                                              
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:32:33
+
+Cannot call `file.walk` because property `walk` is missing in exports [1]. [prop-missing]
+
+   src/admin/search.js:32:33
+   32| 	const directories = await file.walk(path.resolve(nconf.get('views_dir'), 'admin'));
+                                       ^^^^
+
+References:
+   src/file.js
+   ^^^^^^^^^^^ [1]
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:36:19
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at identifier: [signature-verification-failure]
+
+   36| function sanitize(html) {
+                         ^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:36:19
+
+Missing an annotation on `html`. [missing-local-annot]
+
+   36| function sanitize(html) {
+                         ^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:36:24
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at function return: [signature-verification-failure]
+
+   36| function sanitize(html) {
+                              
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:45:19
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at identifier: [signature-verification-failure]
+
+   45| function simplify(translations) {
+                         ^^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:45:19
+
+Missing an annotation on `translations`. [missing-local-annot]
+
+   45| function simplify(translations) {
+                         ^^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:45:32
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at function return: [signature-verification-failure]
+
+   45| function simplify(translations) {
+                                      
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:54:20
+
+Missing an annotation on `namespace`. [missing-local-annot]
+
+   54| function nsToTitle(namespace) {
+                          ^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:61:29
+
+Missing an annotation on `namespace`. [missing-local-annot]
+
+   61| async function initFallback(namespace) {
+                                   ^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:77:25
+
+Missing an annotation on `namespace`. [missing-local-annot]
+
+   77| async function fallback(namespace) {
+                               ^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:87:25
+
+Missing an annotation on `language`. [missing-local-annot]
+
+   87| async function initDict(language) {
+                               ^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:92:31
+
+Missing an annotation on `language`. [missing-local-annot]
+
+   92| async function buildNamespace(language, namespace) {
+                                     ^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------- src/admin/search.js:92:41
+
+Missing an annotation on `namespace`. [missing-local-annot]
+
+   92| async function buildNamespace(language, namespace) {
+                                               ^^^^^^^^^
+
+
+Error --------------------------------------------------------------------------------------- src/admin/search.js:127:30
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at identifier: [signature-verification-failure]
+
+   127| async function getDictionary(language) {
+                                     ^^^^^^^^
+
+
+Error --------------------------------------------------------------------------------------- src/admin/search.js:127:30
+
+Missing an annotation on `language`. [missing-local-annot]
+
+   127| async function getDictionary(language) {
+                                     ^^^^^^^^
+
+
+Error --------------------------------------------------------------------------------------- src/admin/search.js:127:39
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at function return: [signature-verification-failure]
+
+   127| async function getDictionary(language) {
+                                              
+
+
+Error --------------------------------------------------------------------------------------- src/admin/search.js:142:25
+
+`module` may only be used as part of a legal top level export statement [invalid-export]
+
+   142| require('../promisify')(module.exports);
+                                ^^^^^^
+
+
+Error --------------------------------------------------------------------------------------- src/admin/versions.js:9:22
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Cannot
+determine the type of this literal. Please provide an annotation, e.g., by adding a type cast around this expression.
+[signature-verification-failure]
+
+   9| const isPrerelease = /^v?\d+\.\d+\.\d+-.+$/;
+                           ^^^^^^^^^^^^^^^^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------- src/admin/versions.js:12:34
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Missing type
+annotation at function return: [signature-verification-failure]
+
+   12| async function getLatestVersion() {
+                                        
+
+
+Error -------------------------------------------------------------------------------------- src/admin/versions.js:15:71
+
+Cannot get `meta.config` because property `config` is missing in exports [1]. [prop-missing]
+
+   src/admin/versions.js:15:71
+   15| 		'User-Agent': encodeURIComponent(`NodeBB Admin Control Panel/${meta.config.title}`),
+                                                                             ^^^^^^
+
+References:
+   src/meta/index.js
+   ^^^^^^^^^^^^^^^^^ [1]
+
+
+Error -------------------------------------------------------------------------------------- src/admin/versions.js:15:78
+
+Cannot get `meta.config.title` because property `title` is missing in `void` (due to access of non-existent property
+`config`) [1]. [incompatible-use]
+
+   src/admin/versions.js:15:78
+   15| 		'User-Agent': encodeURIComponent(`NodeBB Admin Control Panel/${meta.config.title}`),
+                                                                                    ^^^^^
+
+References:
+   src/admin/versions.js:15:66
+   15| 		'User-Agent': encodeURIComponent(`NodeBB Admin Control Panel/${meta.config.title}`),
+                                                                        ^^^^^^^^^^^ [1]
+
+
+Error -------------------------------------------------------------------------------------- src/admin/versions.js:19:11
+
+Cannot assign `versionCacheLastModified` to `headers['If-Modifie...']` because property `If-Modified-Since` is missing
+in object literal [1]. [prop-missing]
+
+   src/admin/versions.js:19:11
+   19| 		headers['If-Modified-Since'] = versionCacheLastModified;
+                 ^^^^^^^^^^^^^^^^^^^
+
+References:
+   src/admin/versions.js:13:18
+                        v
+   13| 	const headers = {
+   14| 		Accept: 'application/vnd.github.v3+json',
+   15| 		'User-Agent': encodeURIComponent(`NodeBB Admin Control Panel/${meta.config.title}`),
+   16| 	};
+       	^ [1]
+
+
+Error -------------------------------------------------------------------------------------- src/admin/versions.js:44:25
+
+`exports` may only be used as part of a legal top level export statement [invalid-export]
+
+   44| require('../promisify')(exports);
+                               ^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------------- src/als.js:3:39
+
+Cannot resolve module `async_hooks`. [cannot-resolve-module]
+
+   3| const { AsyncLocalStorage } = require('async_hooks');
+                                            ^^^^^^^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------------- src/als.js:5:27
+
+Cannot build a typed interface for this module. You should annotate the exports of this module with types. Cannot
+determine the type of this new expression. Please provide an annotation, e.g., by adding a type cast around this
+expression. [signature-verification-failure]
+
+   5| const asyncLocalStorage = new AsyncLocalStorage();
+                                ^^^^^^^^^^^^^^^^^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------- src/analytics.js:3:25
+
+Cannot resolve module `cron`. [cannot-resolve-module]
+
+   3| const cronJob = require('cron').CronJob;
+                              ^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------- src/analytics.js:4:25
+
+Cannot resolve module `winston`. [cannot-resolve-module]
+
+   4| const winston = require('winston');
+                              ^^^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------- src/analytics.js:5:23
+
+Cannot resolve module `nconf`. [cannot-resolve-module]
+
+   5| const nconf = require('nconf');
+                            ^^^^^^^
+
+
+Error -------------------------------------------------------------------------------------------- src/analytics.js:8:19
+
+Cannot resolve module `lodash`. [cannot-resolve-module]
+
+   8| const _ = require('lodash');
+                        ^^^^^^^^
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:19:19
+
+`module` may only be used as part of a legal top level export statement [invalid-export]
+
+   19| const Analytics = module.exports;
+                         ^^^^^^
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:41:22
+
+Cannot get `meta.config` because property `config` is missing in exports [1]. [prop-missing]
+
+   src/analytics.js:41:22
+   41| 		max: parseInt(meta.config['analytics:maxCache'], 10) || 500,
+                            ^^^^^^
+
+References:
+   src/meta/index.js
+   ^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:41:29
+
+Cannot get `meta.config['analytics:...']` because an index signature declaring the expected key / value type is missing
+in `void` (due to access of non-existent property `config`) [1]. [incompatible-use]
+
+   src/analytics.js:41:29
+   41| 		max: parseInt(meta.config['analytics:maxCache'], 10) || 500,
+                                   ^^^^^^^^^^^^^^^^^^^^
+
+References:
+   src/analytics.js:41:17
+   41| 		max: parseInt(meta.config['analytics:maxCache'], 10) || 500,
+                       ^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:67:30
+
+Missing an annotation on `obj1`. [missing-local-annot]
+
+   67| function incrementProperties(obj1, obj2) {
+                                    ^^^^
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:67:36
+
+Missing an annotation on `obj2`. [missing-local-annot]
+
+   67| function incrementProperties(obj1, obj2) {
+                                          ^^^^
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:81:10
+
+Cannot get `plugins.hooks` because property `hooks` is missing in exports [1]. [prop-missing]
+
+   src/analytics.js:81:10
+   81| 	plugins.hooks.fire('action:analytics.increment', { keys: keys });
+                ^^^^^
+
+References:
+   src/plugins/index.js
+   ^^^^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:81:16
+
+Cannot call `plugins.hooks.fire` because property `fire` is missing in `void` (due to access of non-existent property
+`hooks`) [1]. [incompatible-use]
+
+   src/analytics.js:81:16
+   81| 	plugins.hooks.fire('action:analytics.increment', { keys: keys });
+                      ^^^^
+
+References:
+   src/analytics.js:81:2
+   81| 	plugins.hooks.fire('action:analytics.increment', { keys: keys });
+        ^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/analytics.js:221:9
+
+Cannot use number [1] to assign a computed property. Computed properties may only be numeric or string literal values.
+See https://flow.org/en/docs/types/literals/ for more information on literal types. [invalid-computed-prop]
+
+   src/analytics.js:221:9
+   221| 		terms[term] = parseInt(counts[index], 10) || 0;
+                ^^^^
+
+References:
+   src/analytics.js:215:17
+   215| 		hoursArr.push(hour.getTime() - (i * 3600 * 1000));
+                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------ src/analytics.js:228:23
+
+Cannot access object with computed property using number [1]. Only number literals are allowed, not `number` in general.
+[invalid-computed-prop]
+
+   src/analytics.js:228:23
+   228| 		termsArr.push(terms[hour]);
+                              ^^^^
+
+References:
+   src/analytics.js:215:17
+   215| 		hoursArr.push(hour.getTime() - (i * 3600 * 1000));
+                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------ src/analytics.js:245:32
+
+Missing an annotation on `hour`. [missing-local-annot]
+
+   245| 	async function getHourlyStats(hour) {
+                                       ^^^^
+
+
+Error -------------------------------------------------------------------------------------------- src/api/admin.js:8:18
+
+`module` may only be used as part of a legal top level export statement [invalid-export]
+
+   8| const adminApi = module.exports;
+                       ^^^^^^
+
+
+Error ------------------------------------------------------------------------------------------- src/api/admin.js:11:30
+
+Cannot get `privileges.admin` because property `admin` is missing in exports [1]. [prop-missing]
+
+   src/api/admin.js:11:30
+   11| 	const ok = await privileges.admin.can('admin:settings', caller.uid);
+                                    ^^^^^
+
+References:
+   src/privileges/index.js
+   ^^^^^^^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/api/admin.js:11:36
+
+Cannot call `privileges.admin.can` because property `can` is missing in `void` (due to access of non-existent property
+`admin`) [1]. [incompatible-use]
+
+   src/api/admin.js:11:36
+   11| 	const ok = await privileges.admin.can('admin:settings', caller.uid);
+                                          ^^^
+
+References:
+   src/api/admin.js:11:19
+   11| 	const ok = await privileges.admin.can('admin:settings', caller.uid);
+                         ^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/api/admin.js:16:13
+
+Cannot get `meta.configs` because property `configs` is missing in exports [1]. [prop-missing]
+
+   src/api/admin.js:16:13
+   16| 	await meta.configs.set(setting, value);
+                   ^^^^^^^
+
+References:
+   src/meta/index.js
+   ^^^^^^^^^^^^^^^^^ [1]
+
+
+Error ------------------------------------------------------------------------------------------- src/api/admin.js:16:21
+
+Cannot call `meta.configs.set` because property `set` is missing in `void` (due to access of non-existent property
+`configs`) [1]. [incompatible-use]
+
+   src/api/admin.js:16:21
+   16| 	await meta.configs.set(setting, value);
+                           ^^^
+
+References:
+   src/api/admin.js:16:8
+   16| 	await meta.configs.set(setting, value);
+              ^^^^^^^^^^^^ [1]
+
+
+
+... 19421 more errors (only 50 out of 19471 errors displayed)
+To see all errors, re-run Flow with --show-all-errors
diff --git a/install/package.json b/install/package.json
index cb5eb4e4ea..1e16b74fa9 100644
--- a/install/package.json
+++ b/install/package.json
@@ -10,6 +10,7 @@
     },
     "main": "app.js",
     "scripts": {
+        "flow": "flow",
         "start": "node loader.js",
         "lint": "eslint --cache ./nodebb .",
         "test": "nyc --reporter=html --reporter=text-summary mocha",
@@ -160,6 +161,7 @@
         "eslint": "8.57.0",
         "eslint-config-nodebb": "0.2.1",
         "eslint-plugin-import": "2.29.1",
+        "flow-bin": "^0.250.0",
         "grunt": "1.6.1",
         "grunt-contrib-watch": "1.1.0",
         "husky": "8.0.3",
@@ -195,4 +197,4 @@
             "url": "https://github.com/barisusakli"
         }
     ]
-}
\ No newline at end of file
+}
diff --git a/src/topics/tools.js b/src/topics/tools.js
index e092d7680e..be699263e9 100644
--- a/src/topics/tools.js
+++ b/src/topics/tools.js
@@ -1,3 +1,4 @@
+
 'use strict';
 
 const _ = require('lodash');