Which Python packages are available?+
NumPy, and the full Python standard library (math, json, re, datetime, collections, itertools, functools, etc.). For additional packages, use micropip: import micropip; await micropip.install('package-name').
Can I use print() to see output?+
Yes. The runner captures stdout and displays it in the terminal panel below the editor. print() works exactly as you'd expect.
Why does it take a few seconds to start?+
Pyodide is a ~10 MB WebAssembly bundle that has to download and initialise the first time. After that, execution is fast.
Is my code sent to a server?+
No. Pyodide runs Python entirely in your browser using WebAssembly - your code never leaves your device.
Which Python version does the online interpreter use?+
The interpreter uses Python 3.11 via Pyodide. Most Python 3.10+ syntax and standard library features are fully supported. Check pyodide.org for the exact version bundled with this tool.
What Python libraries are pre-installed?+
NumPy, and the full CPython standard library (math, json, re, datetime, collections, itertools, functools, csv, and more). Install additional packages at runtime with: import micropip; await micropip.install('package-name').
Can I read or write files in the browser Python interpreter?+
Pyodide provides a virtual in-memory filesystem. You can use open(), read(), and write() for text processing within a session. Files are not persisted between page reloads, and you cannot access your local filesystem directly from the browser.
How does this compare to running a Jupyter notebook?+
Both run Python in the browser, but Jupyter notebooks have cells, output inline with code, and rich display for dataframes and charts. This interpreter is simpler - a code editor with a terminal-style output. Use this for quick script testing; use JupyterLite for data science and notebook-style workflows.