Run Python code online
Run Python code online in your browser with Pyodide. Practice algorithms, use standard-library modules, and see output without a Python installation.
Practice interview code in your browser
Use the editor above to try algorithms, change the sample input, and run a focused snippet. The terminal displays program output and errors so you can iterate quickly.
Example program
Start with this interview-style example, then modify it to test edge cases and alternative approaches.
from collections import Counter
def first_unique(text):
counts = Counter(text)
return next((ch for ch in text if counts[ch] == 1), None)
print(first_unique("swiss"))Runtime and compatibility
The first run downloads the Pyodide WebAssembly runtime. Pure Python standard-library code works well; third-party packages must have a Pyodide-compatible build. Browser code cannot access your computer’s files directly.
Frequently asked questions
Where does Python run?
Pyodide runs CPython compiled to WebAssembly in your browser. Your source and output stay on your device.
Can I use pip?
You can use packages that provide a Pyodide-compatible wheel. Arbitrary native packages are not supported.
Why is the first run slower?
The browser downloads and initializes the Python WebAssembly runtime the first time. Later runs reuse the loaded runtime for that page session.