Online Python compiler
Write Python 3, press ▶ Run. Real CPython 3.14 runs in your browser with numpy, pandas and matplotlib, input() and a line-by-line visualizer. No signup, no queue; your code stays on your device.
name = "world"
print(f"Hello, {name}!")
for i in range(1, 4):
print(f"{i} squared is {i * i}")
Run Python online, no install
The editor above is a full Python 3 environment: loops, classes, generators, async, f-strings, the match statement and the standard library all work. Tab indents, Enter keeps your indentation, and Ctrl/⌘ + Enter runs the code.
Press Visualize to replay your program one line at a time with the call stack and every variable shown, like a debugger you can rewind. ↓ .py downloads the file.
Stuck on an error? Press Fix the error and the AI reads your code together with the traceback, explains what went wrong and offers corrected code you can drop back into the editor.
What works and what doesn’t
- Works: the standard library, numpy, pandas, matplotlib charts and scipy (loaded on first import),
input()through the stdin box, files written and read in the same run (an in-memory filesystem), recursion, long loops (up to 20 seconds). - Doesn’t: network sockets,
subprocess, threads, GUI toolkits like tkinter, and PyPI packages that ship native code not built for WebAssembly.
Need syntax help while you code? Keep the Python cheat sheet open in another tab; every snippet there opens straight in this compiler. Want to watch your code run step by step? Open the Python visualizer, or paste broken code into the Python code checker to find syntax errors without running it. For the one-liners that confuse most learners, see the list comprehension explainer and the f-string format builder.
Frequently asked questions
Is this a real Python interpreter?
Yes. It runs CPython 3 compiled to WebAssembly (the Pyodide project) inside a Web Worker in your browser. It is the same interpreter as desktop Python, not a simulation.
Does my code get sent to a server?
No. Code runs entirely on your device. The only time code leaves your browser is if you click an AI button (Explain or Fix), which sends that code to the AI model to answer.
Which modules can I import?
The whole standard library works out of the box. Popular scientific packages built for Pyodide, including numpy, pandas, matplotlib and scipy, load automatically the first time you import them (a one-off download of a few MB each). Network sockets, threads and subprocesses are not available in the browser sandbox.
Can I plot charts with matplotlib?
Yes. Import matplotlib.pyplot, build your figure and call plt.show(); every open figure is rendered as an image in the output panel. Load the “matplotlib chart” example to try it.
What does the Visualize button do?
It runs your program under a tracer and records every line it executes (up to 400 steps). You can then step forwards and backwards to see the current line, the call stack and the value of every variable, which is the fastest way to understand a loop or a recursive function.
Which Python version is this?
Python 3.14 (CPython built for WebAssembly by the Pyodide project, version 314.0.7). The version is shown in the status bar once the runtime has loaded.
How does input() work?
Type the lines your program will read into the stdin box under the editor before pressing Run. Each input() call reads the next line.
Why is the first run slower?
The Python runtime (about 12 MB) is downloaded and started on the first run. After that your browser caches it and runs start in milliseconds.
Can I save or share my code?
Your code is saved automatically in this browser (localStorage). The Share button puts your code into the page URL so anyone with the link sees the same snippet; nothing is stored on a server.