Code Playgrounds

Full ES2015+ JavaScript playground. console.log output, error catching, 6 example snippets. Runs natively in your browser.

Real CPython 3.12 via Pyodide (WebAssembly). Full standard library — math, json, datetime, itertools, dataclasses, typing and more. ~8MB first load, cached after.

Real SQLite via sql.js (WebAssembly). CREATE tables, INSERT rows, SELECT with JOINs, aggregates, window functions, CTEs. Results as formatted tables. ~1MB first load, cached after.

Real TypeScript 5.9 compiler, running client-side. Transpiles and executes your code with console output — syntax-checked, not fully type-checked (see page for the honest scope note).

Official JetBrains Kotlin Playground widget — real compilation and execution on JetBrains' own servers, the same backend that runs kotlinlang.org's examples.

Links to the official Go Playground (go.dev/play) — the same tool Go's own docs use. Real compilation on Google's servers.

Links to the official Rust Playground (play.rust-lang.org) — real rustc, stable/beta/nightly, top 100 crates available.

Links to Compiler Explorer (godbolt.org) — a widely-used, established online compiler supporting real Java compilation.

Links to Compiler Explorer (godbolt.org) — real GCC/Clang, the same tool this project used to compile-audit its C content.

Links to Compiler Explorer (godbolt.org) — the tool C++ built Godbolt for in the first place. Real GCC/Clang.

Links to Compiler Explorer (godbolt.org) — a real Swift toolchain, since Apple's own Swift Playgrounds is a native app, not a website.