Muon Save

GPU based Electron on a diet

Project README


GitHub code size in bytes

Muon is a lightweight alternative to Electron written in Golang in about ~300 LoC, using Ultralight instead of Chromium. Ultralight is a cross-platform WebKit rewrite using the GPU to target embedded desktop applications that resulted in a fast, lightweight, and low-memory HTML UI solution that blends the power of Chromium with the small footprint of Native UI.


  • Full JS to Go interop
  • GPU based rendering
  • Cross-platform
  • Hot-reloading
  • Superior disk size + memory & cpu usage

Comparison with a "Hello, World!" React App

Muon Electron
CPU 0.0% 1.2%
MEM 26.0 MB 201.7 MB
DISK 42 MB 136 MB


From examples/create-react-app/main.go:

package main

import (


func main() {
  // Any static asset packer of your liking (ex. fileb0x)
  fileHandler := http.FileServer(webfiles.HTTP)

  cfg := &muon.Config{
    Title:      "Hello, World!",
    Height:     500,
    Width:      500,
    Titled:     true,
    Resizeable: true,

  m := muon.New(cfg, fileHandler)

  // Expose our `add` function to the JS runtime
  m.Bind("add", add)

  // Show the Window and start the Runtime
  if err := m.Start(); err != nil {

// Muon automatically handles interop to and from the JS runtime
func add(a float64, b float64) float64 {
  return a + b


Q: How are JS types translated to Go types?

  • JS: Boolean Go: bool
  • JS: Number Go: float64
  • JS: String Go: string
  • JS: Object Go: struct via JSON

Q: How do I setup Ultralight?

Q: Is there perfect Chrome or Firefox feature parity?

Q: How do I get rid of the Console on Windows?

  • Add -ldflags -H=windowsgui to either your go build or go run to get rid of the window.

Q: I get exit status 3221225781

  • Your program likely can't find the Ultralight libraries. Ensure they're either installed on the system, or, in the same folder as your program. Currently, Muon uses the 1.1 Ultralight pre-release that hasn't yet propagated to their main site and can only be downloaded from the Ultralight github repo.

Q: I get cannot open shared object file

  • If you're attempting to load the libraries out of the same directory as your program add -ldflags "-r ." to your go build to set rpath to the local directory for library resolution.

Q: I get symbol not found: ulCreateSettings

  • This likely means you're not using the 1.1 Ultralight pre-release which can be downloaded only from their GitHub Repo for now

Q: How do I compile for x86?

  • Currently, Ultralight only supports Windows for x86. Ensure you have a 32-bit gcc in your path, and ensure you have CGO_ENABLED=1 and GOARCH=386 environment variables set.


While muon itself is MIT licensed, Ultralight is not.

Ultralight is free for non-commercial use, educational use, 
and also free for commercial use by small indie developers making
less than US$100,000 a year. You can find full terms in the SDK. 
Pricing plans for larger commercial projects will be announced later.

Their specific license terms can be found here.

Open Source Agenda is not affiliated with "Muon" Project. README Source: ImVexed/muon
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1 year ago

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