How to run Python online
- Type or paste Python code, or pick an example.
- Press Run (or Ctrl/Cmd + Enter). The first run downloads the Python runtime, which takes a few seconds; after that, runs start instantly and the runtime is cached by your browser.
- Output from
print()appears on the right, and errors show the full traceback.input()opens a prompt so interactive scripts work. - Your code is saved in your browser; download it as a
.pyfile to keep it.
Real CPython in WebAssembly
This runner uses Pyodide, a port of the official CPython 3.12 interpreter to WebAssembly. That means real Python semantics and almost the whole standard library: datetime, json, re, collections, itertools, statistics, decimal and more. Popular scientific packages, including NumPy, pandas, SciPy, scikit-learn and Matplotlib, are installed automatically when you import them.
It is a convenient way to practise Python, check a snippet from a tutorial, do homework on a school Chromebook or tablet where you cannot install software, or crunch a quick calculation. Because it runs locally, it also works for code that processes private data.
Limitations
Code runs on the page's main thread, so a long or infinite loop will freeze the tab until it finishes; reload the page to stop it. Files you open are not on your disk, there is no subprocess or socket access, and packages with native code must be available as Pyodide builds. Pure-Python packages from PyPI can be installed with import micropip; await micropip.install("name").
Is my code sent to a server?
No. Only the Python runtime is downloaded from a CDN. Your code runs entirely inside your browser and is never uploaded.
Which Python version is this?
CPython 3.12, via Pyodide 0.26.4.
Can I use pandas and NumPy?
Yes. Just import them. They are downloaded the first time you use them, which can take a few seconds on a slow connection.