Rust in your browser

Miri, Rust's own interpreter, built for WebAssembly, interprets your program rather than compiling it — nothing leaves the page.

Runtime

The first Run downloads Miri and the Rust standard library (about 60 MB compressed, 156 MB unpacked) into a sandbox on a separate origin. Later visits load them from your browser's cache.

Not loaded yet — press Run to download Miri and the Rust standard library.

Downloaded: —
Toolchain: —
Runs as: Interpreted MIR, WASI

Rust scratchpad

Write a whole program with a main function and run it. Stop ends a long-running program by shutting down its worker.

Experimental: this is a 2024 development build of Rust (1.78) and Miri, published by the rubri project. It runs the standard library only (no crates), it is slow (every step is interpreted, with Miri's undefined-behaviour checks turned off), and a panic ends the program instead of unwinding.

Output will appear here.

Experiments

Ready-made Rust programs. Each is interpreted exactly like the scratchpad.

Pick an experiment.

Runtime probes

Ask Miri what it thinks it is running on, and how fast it interprets, from inside the browser sandbox.

Probe results will appear here.