go-app — Build Progressive Web Apps with Go and WebAssembly

Introduction

go-app is a Go package that lets developers write frontend web applications entirely in Go. Your code compiles to WebAssembly and runs in the browser, while a thin Go HTTP server handles routing and asset delivery. The result is a progressive web app with offline support, installability, and the full type safety of Go.

What go-app Does

• Compiles Go application code to WebAssembly for client-side execution
• Provides a declarative, component-based UI model similar to React
• Generates a service worker and manifest for PWA installability and offline caching
• Handles server-side rendering and prerendering for SEO and fast initial loads
• Manages routing, lifecycle events, and state updates within a single Go codebase

Architecture Overview

go-app works in two modes simultaneously. On the server side, a Go HTTP handler serves the compiled WASM binary, static assets, and an auto-generated HTML shell. On the client side, the WASM binary bootstraps the component tree, mounts it to the DOM, and handles all user interaction. Components follow a lifecycle pattern with OnMount, OnNav, and Render methods. The framework manages a virtual DOM diffing layer that updates only the changed elements.

Self-Hosting & Configuration

• Add go-app to your module with go get github.com/maxence-charriere/go-app/v10
• Build the client WASM binary with GOARCH=wasm GOOS=js go build -o web/app.wasm
• Serve assets via the built-in app.Handler in any Go HTTP server
• Configure the PWA manifest (name, icons, theme color) through app.Handler fields
• Deploy as a single binary plus the WASM file to any hosting provider

Key Features

• Write frontend and backend in the same language with shared types and logic
• Automatic PWA features including service worker generation and offline caching
• SEO-friendly with server-side and prerendering support out of the box
• No JavaScript, TypeScript, or Node.js tooling required in the build pipeline
• Component-based architecture with lifecycle hooks and event handling

Comparison with Similar Tools

• Wails compiles Go for native desktop apps; go-app targets the browser via WebAssembly
• Vecty is another Go-to-WASM framework but lacks built-in PWA and SSR support
• Lorca uses Chrome as a UI shell; go-app runs entirely in the browser without requiring Chrome
• React/Next.js requires JavaScript and Node.js; go-app keeps everything in Go
• Fyne builds native desktop UIs with Go; go-app delivers web UIs through the browser

FAQ

Q: How large is the resulting WASM binary? A: A minimal go-app binary starts around 5-8 MB. Using TinyGo or wasm-opt can reduce this. Gzip compression brings the transfer size to roughly 1-2 MB.

Q: Can I use existing JavaScript libraries? A: Yes. go-app provides js.Value interop to call JavaScript functions and access browser APIs from Go code.

Q: Does go-app support hot reloading during development? A: Not natively, but you can use tools like air or entr to watch for file changes and rebuild the WASM binary automatically.

Q: Is go-app suitable for large applications? A: go-app scales well for medium-complexity apps. For very large SPAs, the WASM binary size and Go's garbage collector pauses in WASM are factors to evaluate.

Sources

• https://github.com/maxence-charriere/go-app
• https://go-app.dev