Five Open-Source Flutter Apps Worth Reading the Source Of

The fastest way to level up as a Flutter developer isn’t another tutorial — it’s reading how production apps with real users solve the problems you’re about to hit. Five of the most-starred Flutter projects on GitHub are unusually good teachers, and each teaches a different lesson.

Sources: GitHub REST API metadata for each repository, fetched October 2026; Flutter topic on GitHub. Star counts move daily.

The lineup

App	Repo	Stars (Oct 2026)	Primary language	License
RustDesk	rustdesk/rustdesk	~125k	Rust (Flutter UI)	AGPL-3.0
Immich	immich-app/immich	~115k	TypeScript server, Flutter app	AGPL-3.0
LocalSend	localsend/localsend	~93k	Dart	Apache-2.0
AppFlowy	AppFlowy-IO/AppFlowy	~77k	Dart	AGPL-3.0
Spotube	KRTirtho/spotube	~50k	Dart	See repo

RustDesk — Flutter UI over a Rust core

RustDesk is a remote-desktop tool (the open-source TeamViewer alternative) whose UI is Flutter while the heavy lifting — encoding, networking, platform plumbing — lives in Rust. The lesson: Flutter is not the whole stack. Look at how it crosses the language boundary (flutter_rust_bridge-style bindings), how the Dart layer stays a thin presentation shell, and how a codebase that must run on desktop and mobile keeps its platform-specific code out of the widget tree.

If you’ve ever wondered “can Flutter handle a real-time, performance-sensitive product?”, this is the proof — and the reading material.

Immich — a Flutter client inside a polyglot system

Immich is a self-hosted Google Photos replacement. Its server is NestJS/Node with a Svelte admin UI; its mobile app is Flutter. The lesson: Flutter as the client tier of a system you don’t fully control. Study how it models a large sync-heavy domain (albums, assets, background upload), how it handles offline state and pagination, and how the team keeps a fast-moving TypeScript backend from breaking the app. It’s also a masterclass in what “self-hosted friendly” means for a mobile client.

LocalSend — one codebase, zero servers, six platforms

LocalSend is an open-source AirDrop alternative: peer-to-peer file transfer over the local network, no accounts, no cloud. The lesson: platform integration done carefully. Networking (NSD/Bonjour, multicast), permissions, firewalls, and background behavior all differ per OS, and the app has to make discovery just work on Android, iOS, Windows, macOS and Linux. It’s also refreshingly lean — a good project to read end-to-end in an afternoon rather than a million-line monolith.

AppFlowy — a Notion alternative, and a Flutter architecture lab

AppFlowy bills itself as the leading open-source Notion alternative, and at ~77k stars it’s one of the most ambitious Flutter products in existence. The lessons are architectural: how you layer a document/editor domain (blocks, databases, view trees) over local storage with sync, how it isolates platform and backend concerns behind interfaces, and how a team keeps a large Dart codebase navigable. Its move toward Rust-backed storage and AI features is a case study in where to draw the boundary between Dart and native code.

Spotube — desktop-first Flutter, and shipping outside the stores

Spotube is a music streaming client aimed at desktop and mobile, built in Dart/Flutter with a desktop-first mentality. The lessons: Flutter desktop realities — window management, tray icons, keyboard navigation, packaging — and product engineering that lives largely outside the app stores (auth flows, third-party APIs, distribution via GitHub releases and package managers). If your target is Windows/macOS/Linux as much as phones, read how Spotube lays out its project structure and feature modules.

How to read them (without drowning)

1. Pick a question, not a project. “How do they handle offline sync?” beats “read all of Immich”.
2. Start at pubspec.yaml. Dependencies tell you the architecture: state management, networking, storage, DI.
3. Find the feature boundary. Look for lib/features/... or equivalent; ignore generated files (*.g.dart, *.freezed.dart).
4. Trace one screen end to end: widget → controller/notifier → repository → data source.
5. Check the docs folder and contribution guide — mature projects document their decisions (ADRs, wiki, docs site).

All five are actively maintained, and all are licensed for learning and (with the AGPL caveat) reuse: AGPL means if you ship a modified version as a service or app, you owe the source back — worth knowing before you fork one into your product.

The common thread

Every one of these apps validates the same set of Flutter bets: a single codebase reaching multiple platforms, custom rendering for consistent UI, and Dart as a productive application language — paired, in every case, with serious engineering around state, storage and native interop. That combination, not the framework alone, is what shipped them to hundreds of thousands of stars’ worth of users.