diff --git a/eslint/mandatory.eslint.config.js b/eslint/mandatory.eslint.config.js
new file mode 100644
index 00000000..e3036508
--- /dev/null
+++ b/eslint/mandatory.eslint.config.js
@@ -0,0 +1,86 @@
+import tseslintPlugin from '@typescript-eslint/eslint-plugin';
+import { defineConfig } from 'eslint/config';
+import globals from 'globals';
+
+const backendLanguageOptions = {
+    globals: {
+        // Current, intentionally supported globals
+        extension: 'readonly',
+        config: 'readonly',
+        global_config: 'readonly',
+
+        // Older not entirely ideal globals
+        use: 'readonly', // <-- older import mechanism
+        def: 'readonly', // <-- older import mechanism
+        kv: 'readonly', // <-- should be passed/imported
+        ll: 'readonly', // <-- questionable
+
+        // Language/environment globals
+        ...globals.node,
+    },
+};
+
+export default defineConfig([
+    {
+        ignores: [
+            'src/backend/src/modules/apps/AppInformationService.js', // TEMPORARY - SHOULD BE FIXED!
+            'src/backend/src/services/worker/WorkerService.js', // TEMPORARY - SHOULD BE FIXED!
+            'src/backend/src/public/**/*', // We may be able to delete this! I don't think it's used
+
+            // These files run in the worker environment, so these rules don't apply
+            'src/backend/src/services/worker/dist/**/*.{js,cjs,mjs}',
+            'src/backend/src/services/worker/src/**/*.{js,cjs,mjs}',
+            'src/backend/src/services/worker/template/puter-portable.js',
+        ],
+    },
+    {
+        plugins: {
+            '@typescript-eslint': tseslintPlugin,
+        },
+    },
+    {
+        files: [
+            'src/backend/**/*.{js,mjc,cjs}',
+            'extensions/**/*.{js,mjc,cjs}',
+            'src/backend-core-0/**/*.{js,mjc,cjs}',
+        ],
+        ignores: [
+            'src/backend/src/services/database/sqlite_setup/**/*.js',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            ...backendLanguageOptions,
+        },
+    },
+    {
+        files: [
+            'src/backend/src/services/database/sqlite_setup/**/*.js',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            globals: {
+                read: 'readonly',
+                write: 'readonly',
+                log: 'readonly',
+                ...globals.node,
+            },
+        },
+    },
+    {
+        files: [
+            'src/backend/**/*.{ts}',
+            'extensions/**/*.{ts}',
+            'src/backend-core-0/**/*.{ts}',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            ...backendLanguageOptions,
+        },
+    },
+]);
diff --git a/package.json b/package.json
index c80a3839..d559ca78 100644
--- a/package.json
+++ b/package.json
@@ -44,7 +44,7 @@
     "start": "node ./tools/run-selfhosted.js",
     "prestart": "npm run build:ts",
     "dev": "npm run build:ts && DEVCONSOLE=1 node ./tools/run-selfhosted.js",
-    "build": "npm run build:ts; cd src/gui; node ./build.js",
+    "build": "npx eslint --quiet -c eslint/mandatory.eslint.config.js src/backend/src extensions && npm run build:ts && cd src/gui && node ./build.js",
     "check-translations": "node tools/check-translations.js",
     "prepare": "husky",
     "build:ts": "tsc",