Run Racket online

Run Racket 8 online — the language-oriented Scheme.

Version

Firecracker microVM live per-test verdicts multi-file compile

Racket started as PLT Scheme and is now its own thing: a batteries-included, language-oriented Lisp with a very serious macro system. Famous for teaching (via the How to Design Programs curriculum) and language experimentation.

ls-judge runs Racket 8 inside a Firecracker microVM.

Starter code

What you get in Racket

Clicking "Run now" opens the playground with this exact code and a matching test case pre-loaded — passes on first Run.

racket

Racket 8

#lang racket
(define n (string->number (read-line)))
(displayln (* n 2))

stdin →

expected →

FAQ

Common questions about Racket on ls-judge

Which Racket?: Racket 8.x on the Chez Scheme backend.
raco pkg installs?: No — sandbox has no network. Bundled packages only.
Typed Racket?: Yes, via `#lang typed/racket`.
Free?: Yes.