Python in your browser

Real CPython 3.14, compiled to WebAssembly by Pyodide, running in a sandbox — nothing leaves the page.

Runtime

The first Run downloads CPython and its standard library (about 13.5 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 Python.

Downloaded: —
Python version: —
Runtime: Pyodide 314.0.7

Python scratchpad

Write Python and run it; the value of a final expression is shown after the output. Stop ends a runaway program by shutting down its worker.

The standard library is built in. Packages such as numpy load on first import from the pinned Pyodide 314.0.7 release, each checked against its lock-file hash.

Output will appear here.

Experiments

Ready-made Python programs using only the standard library. Each runs exactly like the scratchpad.

Pick an experiment.

Runtime probes

Ask Python what it can see from inside the browser sandbox.

Probe results will appear here.