Online Python compiler
This runs real CPython 3.14 inside your browser. Your code never leaves this tab.
Press Run. The CPython 3.14 engine (about 5 MB) downloads once on your first run, then stays cached.
// Free tool
This runs real CPython 3.14 inside your browser - the actual interpreter compiled to WebAssembly, not a sandbox on a server. Comprehensions, dataclasses, generators and f-strings all behave exactly as they do locally, and importing numpy or pandas pulls the real wheel.
Nothing you type is sent to a server. Your code is saved only in this browser, the engine is downloaded once and cached, and once it has loaded the page keeps running your code with the network off. No account, no sign-in, no limit on how many times you press Run.
// What you get
CPython 3.14 (Pyodide), in a browser tab
Real CPython, compiled to WebAssembly. Not a subset and not a transpiler - the same interpreter, running in your tab.
What it supports
- Python 3.14 with the standard library: collections, itertools, math, json, re, dataclasses, typing, textwrap and the rest.
- numpy and pandas. An import of either fetches the real wheel the first time you run it.
- stdin, stdout and stderr, kept apart, so a program that writes to sys.stderr reads as it would in a terminal.
What it does not
- No network and no filesystem: requests, socket and open() have nothing behind them here.
- pip install cannot run. numpy and pandas are the packages carried on our mirror; anything else is unavailable.
- A program is stopped after 10 seconds.
// Why it runs here
Your code never leaves the tab
Most online compilers send your code to a server, run it in a container, and send the output back. That means a queue when the site is busy, a hard cap on how long your program may run, and a copy of your code on someone else's disk. This one downloads the compiler instead, once, and runs everything locally from then on.
No upload, no account
- The compiler is fetched once and cached; your source is never sent anywhere.
- Nothing is stored on our side. Your code is kept in this browser only, so it is still here when you come back.
- Once the engine has loaded, it keeps running with the network off, which a hosted sandbox cannot do.
Then practice it for real
- A runner tells you what your code printed. It cannot tell you whether you have learned anything.
- Prepshotz runs the same engines against real test cases and grades the result.
- Practice Python with graded problems →
// The other nine
Every language we run, free
// Questions
Python in the browser - FAQ
01Is this really CPython?
Yes. Pyodide is CPython 3.14 itself compiled to WebAssembly, so the interpreter running your code is the reference implementation rather than a rewrite. Integer precision, float repr and the standard library all behave as they do on your machine.
02Can I use numpy or pandas?
Yes. Importing either fetches the real wheel the first time you run a program that needs it, which costs a few megabytes once and is cached afterwards. Packages beyond those two are not available, because pip cannot reach a network from inside the sandbox.
03Does my code get uploaded anywhere?
No. The compiler runs inside your browser tab, so your code never leaves your machine. There is no server to send it to and nothing is logged on our side. Your code is kept only in this browser, and a share link carries it inside the link itself.
04Is it really free, and do I need an account?
Yes, and no. Every tool here runs without an account, a card, or a sign-in. They are free because they cost us nothing per run: the compiler is downloaded to your browser once and your own machine does the work.
05Does it work offline?
Once the engine has loaded, yes: the page keeps running your code with the network off, because nothing it does needs a server. Opening the page needs a connection, but the engine stays cached, so a later visit skips the download.