Firebase now experimentally supports Dart for Cloud Functions, allowing Flutter developers to write backend code in the same language as their frontend. This comprehensive guide covers the full-stack Dart architecture: how Dart Cloud Functions work (using `fireUp`, `onRequest`, `onCall`), the Dart Firebase Admin SDK for Firestore and Authentication operations, step-by-step setup and local emulator usage, deploying to production, calling functions from Flutter, and creating a shared Dart package to eliminate data model duplication between client and server. Key limitations are clearly documented: only HTTP and callable functions can be deployed (no background triggers yet), `httpsCallable` by name doesn't work (use `httpsCallableFromURL` instead), and Dart functions don't appear in the Firebase Console.
