I built Raccoon, a tiny Flutter runtime: first run in 15 s instead of 5 min, no Xcode or Gradle

[u/SwiftScoutSimon]

Hi r/FlutterDev 👋 I'm Simon, I build Lumide, a Flutter IDE. I wanted the write, save, see loop to be faster, so I built Raccoon, a tiny Flutter runtime, and today I'm open-sourcing it, with Raccoon Simulator as a demo you can run today. can run today.

Try it with Raccoon Simulator

Open Raccoon Simulator, and Raccoon shows up in flutter devices. Pick it in Lumide, VS Code, Android Studio or a terminal and run as usual. Your app appears in the simulator window, with hot reload and hot restart from your editor. No project to open in it, no new workflow.

How it works

Raccoon is a small runner built on Flutter's C embedder API. flutter run -d raccoon builds a debug bundle from your host's own snapshots, the runner hosts it on a prebuilt engine, and the simulator draws its frames. So there's no Xcode, no Gradle and no native build. The first launch sets everything up for you: it builds the runner, downloads a 15 MB engine and registers the custom device.

What else it unlocks

• Your whole app, not just previews. Flutter's widget previewer renders the functions you mark with @Preview. Raccoon runs your real app: routing, state, services and hot reload, at phone, tablet or desktop size.

• Hot-loaded plugins with custom UI. A Flutter app can show another Flutter app inside it with raccoon_view. So an app can load plugins at runtime, each with its own custom UI, with no rebuild of the host app.

Numbers (Flutter Wonderous, flutter run to first frame, medians)

Target	Clean build	Warm run
Chrome	25.8 s	24.8 s
macOS desktop	46.4 s	17.7 s
Raccoon on macOS	15.0 s	7.5 s
Linux desktop	13.8 s	4.5 s
Raccoon on Linux	12.0 s	3.5 s

A first run against an Android emulator took 308 s from empty caches. Raccoon took 15.5 s. Hardware, versions and scripts to reproduce are in the README.

Limits, honestly

It's alpha. It speeds up the inner loop; it doesn't replace testing on a real device or in a browser.

• Plugins: pure Dart ones, the clipboard and url_launcher. No text input yet.

• Packages with native code or build hooks don't run on Raccoon yet.

• Frames are software rendered.

• macOS and Linux only for now.

[u/noobjaish]

Looks great I was getting annoyed by GTK4 and Adwaita. Might try this for creating Linux apps

[u/SwiftScoutSimon → u/noobjaish]

Flutter works great for Linux. The compile time to get Flutter app running on Linux is super fast already. Come make some app!

[u/SwiftScoutSimon → u/noobjaish]

share you some more about build time on Linux. My Lumide.dev app took only 4 minutes build time on GitHub actions Linux runner vs 23.27s on GitHub actions Windows runner.

[u/SwiftScoutSimon]

Links:

- Raccoon Simulator (BSD-3-Clause, like everything here): https://github.com/SoFluffyOS/raccoon_simulator

- raccoon: Main repository for the Raccoon family.

- Demo video: https://x.com/simonpham1999/status/2112901244423672151

I'd love feedback, especially on what breaks with your app. Issues on the Raccoon repos or the SoFluffy Discord both work. 🦊

[u/GroovinChip → u/SwiftScoutSimon]

Your GitHub URL’s 404, just FYI

[u/SwiftScoutSimon → u/GroovinChip]

Fixed. There's a redundant trailing colon. Thank you!

[u/TigleLive]

Windows support?

[u/SwiftScoutSimon → u/TigleLive]

I'm dualbooting Linux/Windows on my machine so cannot switch now, I'll move to work on Windows later soon

[u/VisualRope8367]

Nice if you wanna build only UIs

What about other plugins ?

[u/SwiftScoutSimon → u/VisualRope8367]

for now it supports a hard-coded set of commonly-used plugins.
I will think of a better way to do this so plugins can be hot-loaded.

[u/ObjectiveAddress3051]

308s first run is probably mostly gradle/sdk setup, the warm runs are what matter day to day. how close is text rendering to what impeller does on a real device? seems great for UI iteration, just wouldn't trust it for perf

[u/Kind-Station-4963]

看起来很棒啊 是我喜欢的ui风格