Goblox

goblox is a Go playground that runs entirely client-side. Rather than shipping Go off to a server, Yaegi, the Go interpreter, is compiled to WebAssembly and executed in the browser, so there are no API calls and no serverless functions behind it at all.

The UI is a Next.js app with the Monaco editor and Go syntax highlighting on custom zinc themes, auto-completions for the standard library packages like fmt, strings, os and json, a resizable editor and output split, a stdin panel so fmt.Scan and bufio.Scanner actually work, a run timer, keyboard shortcut to run, light and dark themes, and a progress bar while the WASM module boots.

Because Yaegi interprets rather than compiles, plenty does not behave the way it would in a real toolchain, so there is a capabilities page that spells out exactly what works and what does not. The end-to-end suite runs in Playwright, fifteen tests, to keep the whole client-only path honest.