Online Python Compiler: write and run Python 3 in your browser

Python 3.14

main.py

Output

Output appears here when you press Run.

Input

What is Python?

Python is a general-purpose programming language known for code that reads almost like plain English. It is the most widely taught first language, and the standard tool for data analysis, machine learning, automation and scripting, largely thanks to libraries such as NumPy and pandas.

Why use an online Python compiler?

  • Nothing to install. No interpreter, no virtual environment, no PATH to fix. Open the page and start writing, on any computer, including one you cannot install software on.
  • Try an idea in seconds. Check how a slice, a comprehension or an f-string behaves without opening a project.
  • Practise as you learn. Run the examples from a course or tutorial as you read them, change them, and see what breaks.

Example

main.py
scores = {"Asha": 88, "Rohan": 72, "Meera": 95}

for name, score in sorted(scores.items(), key=lambda item: -item[1]):
    grade = "A" if score >= 85 else "B"
    print(f"{name:<6} {score}  {grade}")
Output
Meera  95  A
Asha   88  A
Rohan  72  B

About Gradient Learning's Python Compiler

It runs real CPython 3.14 entirely inside your browser, so your code never leaves your computer. Errors come back as ordinary Python tracebacks pointing at your line numbers in main.py, the same as on your own machine.

What can you do with it?

  • Write and run Python 3 programs, free, with no sign-up
  • Import the standard library and data libraries such as NumPy and pandas
  • Feed your program input for input() calls
  • Open a .py file, and download your code as main.py
  • Stop a program that runs too long, with one click

How to use the tool

  1. Write or paste your code into the main.py panel on the left.
  2. If your program uses input(), open Program input under the editor and type one line for each call.
  3. Press Run, or Ctrl+Enter (⌘+Enter on a Mac). Output and any errors appear in the panel on the right.

The first run takes a few seconds while Python itself downloads. After that, runs start straight away.

Frequently asked questions

Is my code uploaded anywhere?

No. Python runs inside your browser, using Pyodide, a build of the standard CPython interpreter for WebAssembly. Your code is never sent to a server, stored or logged. The only download is the Python runtime itself, the first time you press Run.

Which version of Python does it run?

Python 3.14. It is the real CPython interpreter, not a lookalike, so the standard library behaves the way it does on your own machine: dataclasses, collections, itertools, json, re, datetime, statistics and the rest are all there.

Can I use NumPy, pandas and other libraries?

Yes, for the packages Pyodide has built for the browser, which include NumPy, pandas, SciPy, scikit-learn and matplotlib. Just import them: a package is downloaded the first time a program imports it, which takes a few seconds, and it stays loaded for later runs. Libraries that are not in Pyodide's collection cannot be installed with pip here.

How do I give my program input?

Open Program input (stdin) under the editor and type the lines before you press Run, one line for each input() call. Each line your program reads is shown in green in the output, so the transcript reads like a terminal session. If the program asks for more lines than you gave it, input() raises EOFError, as it would locally.

My program never finishes. What do I do?

Press Stop. It shuts the Python runtime down completely, which is the only reliable way to halt an infinite loop, and the next Run starts a fresh one. That restart takes a second or two because the runtime has to load again.

Why does plt.show() not display a chart?

There is no screen attached to the Python runtime here, so matplotlib runs in a non-interactive mode: your plotting code runs, but nothing is drawn on the page, and plt.show() may print a warning saying so. Printed output, tables and calculations all work normally.

Can my program read files or use the internet?

Files your program writes go to a temporary in-memory file system that disappears when you leave the page or press Stop. They never reach your computer's disk. Ordinary network calls such as requests or urllib do not work from inside the browser sandbox.

Is this a compiler or an interpreter?

Strictly, an interpreter. Python compiles your code to bytecode and then interprets it, which is exactly what happens here, the same as running python main.py. Online Python compiler is simply the name most people search for.