§ online python compiler

Online Python compiler.

Run Python online — no install, no sign-up to press Run, works on your phone. numpy and pandas load on first import.

downloading Python runtime…

Saved

First load fetches ~10 MB of Python runtime from a CDN. It's cached after this — subsequent runs are instant.

OutputCtrl/⌘+Enter

› press Run to execute

Stuck in a loop? Press Stop to end the run and reset the interpreter. Each run is also limited to 20 seconds.

Quick run: Ctrl/⌘+Enter inside the editor. On a phone, tap Run ▸ above the code.

What works here

Runs in this compiler

Python 3.12 — the same CPython you would install, compiled to WebAssembly and running inside your browser tab.
The whole standard library: math, random, json, re, datetime, collections, itertools, dataclasses and the rest.
NumPy, pandas, SciPy and matplotlib: they download the first time you import them, then the browser caches them.
Your code auto-saves in this browser as you type, and comes back when you reopen the page on this device.
print() output and full tracebacks appear under the editor; a Stop button ends a runaway loop.
Nothing is uploaded. Your code never leaves your device.

Does not work here

input() does not work: there is no keyboard prompt, so it raises OSError instead of waiting. Put the values in the code instead.
Each run is limited to 20 seconds.
Files you write with open() live only until you reload or press Stop.
Packages outside the Pyodide bundle do not install here.
Network requests reach only sites that allow browser (CORS) requests; most HTML pages do not.
matplotlib figures are not drawn in this editor. Sockets and subprocesses are not available.

Questions

Is this online Python compiler free?: Yes. Running Python here is free, with no card and no time limit on the page. A free account is optional; paid plans only unlock the lessons after the first five.
Do I need an account to run Python here?: No. Type code and press Run. A free account is only needed to keep lesson progress, publish projects and earn the course certificate.
Does NumPy or pandas work in this compiler?: Yes. import numpy or import pandas downloads the package the first time you use it (it takes a few seconds on the first run), and the browser caches it after that. SciPy and matplotlib load the same way; matplotlib figures are not displayed in this editor, so print your numbers instead.
Can I save my code?: Your code is saved automatically in this browser as you type and is restored when you come back on the same device. Clearing site data removes it. Reset restores the starter code.
How is this different from installing Python?: It is the same CPython 3.12, compiled to WebAssembly (Pyodide) so it runs inside your browser tab: no download, no PATH errors, and it works on a phone or a locked college lab machine. The limits: input() raises an error instead of waiting for typing, each run is limited to 20 seconds, files you write vanish when you reload, only packages bundled with Pyodide install, and network calls only reach sites that allow browser requests. For a long-running script, a web server or an arbitrary PyPI package, install Python locally.
Does it work on a phone?: Yes, in Chrome or Safari on Android and iPhone. The first load downloads about 10 MB of the Python runtime, then it is cached, so later visits start fast.

Where to go from a blank editor

Want to tinker rather than compile a program? The Python playground is the same interpreter with a NumPy starter, next to a SQL playground and a notebook. For one line at a time, use the Python terminal.

context · online python compiler

Why this compiler runs in your browser, not on a server

PyRun uses Pyodide, a real CPython build compiled to WebAssembly, so the interpreter runs inside your tab. That is why there is no queue and no upload: the code you type is executed on your own device, and the output you see is what CPython printed. The runtime is fetched once (about 10 MB) and cached by the browser, so the second visit starts fast even on patchy hostel wifi. numpy, pandas, scipy and matplotlib are fetched the same way on first import. It is not a toy REPL for print("hello"): it is the interpreter you would use to test a function before an exam, check an answer from class, or prototype a pandas transform — minus the install. When you want structure instead of a blank page, the lessons use this same runner with graded exercises.

loading…

What works here

Runs in this compiler

Python 3.12 — the same CPython you would install, compiled to WebAssembly and running inside your browser tab.
The whole standard library: math, random, json, re, datetime, collections, itertools, dataclasses and the rest.
NumPy, pandas, SciPy and matplotlib: they download the first time you import them, then the browser caches them.
Your code auto-saves in this browser as you type, and comes back when you reopen the page on this device.
print() output and full tracebacks appear under the editor; a Stop button ends a runaway loop.
Nothing is uploaded. Your code never leaves your device.

Does not work here

input() does not work: there is no keyboard prompt, so it raises OSError instead of waiting. Put the values in the code instead.
Each run is limited to 20 seconds.
Files you write with open() live only until you reload or press Stop.
Packages outside the Pyodide bundle do not install here.
Network requests reach only sites that allow browser (CORS) requests; most HTML pages do not.
matplotlib figures are not drawn in this editor. Sockets and subprocesses are not available.

Questions

Is this online Python compiler free?

Yes. Running Python here is free, with no card and no time limit on the page. A free account is optional; paid plans only unlock the lessons after the first five.

Do I need an account to run Python here?

No. Type code and press Run. A free account is only needed to keep lesson progress, publish projects and earn the course certificate.

Does NumPy or pandas work in this compiler?

Yes. import numpy or import pandas downloads the package the first time you use it (it takes a few seconds on the first run), and the browser caches it after that. SciPy and matplotlib load the same way; matplotlib figures are not displayed in this editor, so print your numbers instead.

Can I save my code?

Your code is saved automatically in this browser as you type and is restored when you come back on the same device. Clearing site data removes it. Reset restores the starter code.

How is this different from installing Python?

It is the same CPython 3.12, compiled to WebAssembly (Pyodide) so it runs inside your browser tab: no download, no PATH errors, and it works on a phone or a locked college lab machine. The limits: input() raises an error instead of waiting for typing, each run is limited to 20 seconds, files you write vanish when you reload, only packages bundled with Pyodide install, and network calls only reach sites that allow browser requests. For a long-running script, a web server or an arbitrary PyPI package, install Python locally.

Does it work on a phone?

Yes, in Chrome or Safari on Android and iPhone. The first load downloads about 10 MB of the Python runtime, then it is cached, so later visits start fast.

Why this compiler runs in your browser, not on a server