Run Brainfuck online

Brainfuck is the minimalist Turing-complete language: eight commands, one memory tape, one instruction pointer. Educational for anyone building their first compiler, a beautiful hazing ritual for anyone else.

ls-judge runs a Brainfuck interpreter in a Firecracker microVM. Programs read stdin one byte at a time (`,`) and write output byte by byte (`.`).

What you get in Brainfuck

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

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Common questions about Brainfuck on ls-judge

What is the tape size?

30000 bytes — the canonical default. Cell values wrap on overflow.

Do you have a JIT?

No, an interpreter — fast enough for anything but the biggest programs.

Do I need an account?

No.

Any output limit?

Yes — 1 MB stdout per job to keep the browser tab responsive.

• Brainfuck — Wikipedia↗