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GPU based Electron on a diet
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Latest commit 467d82e Oct 11, 2019
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examples/create-react-app Example version bump & removed learn react blank target Oct 9, 2019
include Remove unecessary headers Oct 8, 2019
ultralight Added Ultralight license attribution Oct 8, 2019
.gitignore Added support for null and undefined JS types Oct 8, 2019
LICENSE Create LICENSE Oct 7, 2019 Update Oct 11, 2019 Update Oct 10, 2019
go.mod Usability features Oct 8, 2019
logo.svg readme Oct 4, 2019
muon.go fix width/height being used in wrong order Oct 9, 2019
muon_test.go Fixed cgo callbacks Oct 9, 2019


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


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.

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