ExtensionsDeveloper toolsPython Runner

Python Runner iconPython Runner

Run Python code in your browser, offline

You found a few lines on Stack Overflow, in a GitHub issue or in an answer from an AI assistant, and you want to know whether they work. The computer in front of you has no Python, or it is a locked-down work laptop where you cannot install one.

Add to Chrome — free (Python Runner)
Python Runner editor with a short script that builds a JSON report, and the output panel showing count, total and median

Python Runner gives you an editor and an interpreter in a Chrome tab, and it does not need an internet connection.

What it does

Python Runner keeps a CPython interpreter inside the extension, so you can paste a script, press Run and read the output without installing Python.

  • Editor with syntax highlighting, line numbers and auto-indent, in a light or dark theme
  • Run with a button or Ctrl+Enter, and a Stop button that halts even an infinite loop
  • Live output with real CPython tracebacks and line numbers that match the editor
  • A stdin field, so scripts that call input() run as expected
  • Snippets saved on your device and reopened in one click
  • Run selected Python from the right-click menu on any page

How it works

  1. Click the toolbar icon and choose Open Python Runner. There is no sign-up and no daily limit on runs.
  2. Type or paste a script into the editor.
  3. Press Run or Ctrl+Enter. Output streams into the output panel as the script prints it.
  4. The extension ships CPython 3 compiled to WebAssembly (Pyodide), so you get the standard interpreter and its standard library: json, re, datetime, itertools, collections, csv, math and the rest. Every run starts from a fresh namespace, so variables from the previous run do not leak into the next one.
  5. If the script calls input(), type the values into the stdin field first.
  6. Save the script as a snippet if you will need it again; it stays on this device.
Python code selected in online documentation with the right-click menu open on the Run selected Python item
Python code selected in online documentation with the right-click menu open on the Run selected Python item
Toolbar popup reporting that Python is ready, with buttons to open the runner or run selected code on the page
Toolbar popup reporting that Python is ready

Running code straight from a web page

Select a block of Python on any page, right-click and choose Run selected Python. The runner opens in a new tab and executes the selection with its indentation kept. It is a quick way to test an answer before you copy it into a project.

Who it is for

  • Students working through a course can follow along on whatever computer they have.
  • Developers can check a regex, a date calculation or a list comprehension without opening an IDE.
  • Teachers can show output live in class, and because the runner works offline, the school network does not get in the way.

What it can't do

  • Standard library only: numpy, pandas, requests and other pip packages are not available.
  • Python code has no network access, and files do not survive a restart.
  • No graphics output, so matplotlib windows and turtle are out of scope.
  • Runs a whole script at a time rather than one line at a time like an interactive console.
  • The first launch takes a few seconds while the interpreter warms up.

Permissions and your data

Does not read or change any web page on its own.

storage
Keeps your current draft and saved snippets in Chrome's extension storage on this device, along with your settings.
contextMenus
Adds the Run selected Python item to the right-click menu when you select code on a page.
activeTab
Lets the extension read the code you selected on the current tab, only at the moment you click Run selected Python.
scripting
Works with activeTab to fetch that selected text from the page once; the extension does not change pages or run on them otherwise.
Where your data goesYour code runs inside the extension on your device, using CPython compiled to WebAssembly (Pyodide), and scripts cannot reach the network or your files. The extension makes no network requests; drafts and snippets stay in Chrome's extension storage, and settings may sync between your own Chrome profiles through Chrome Sync.

Python Runner guides

Try Python Runner

Free. Remove it any time from the Chrome toolbar.

Add to Chrome — free (Python Runner)