Programming Languages
Ruby Playground
Real CRuby 3 in the browser - blocks, classes, modules, regex.
Runtime: ruby.wasm (CRuby in WebAssembly)
First run downloads ~25 MB of Ruby WASM; subsequent runs are instant.
About this playground
CRuby 3.4 compiled to WebAssembly via wasi-sdk. Real Ruby - same MRI interpreter, same garbage collector, same standard library you'd run locally. The runtime is ~25 MB and lazy-loaded only when you open this page; after that, runs are near-instant.
FAQs
Real CRuby or mruby?
Real CRuby - the official ruby.wasm release is the same MRI interpreter you'd run locally, just built for WebAssembly via wasi-sdk.
How big is the download?
Roughly 25 MB. We lazy-load it on this page only; visitors elsewhere on the site aren't affected.
Will gems work?
Pure-Ruby gems can be required if their source is available. C-extension gems (Nokogiri, RGeo, Bcrypt) need a POSIX build environment and won't load here.