Python Runner

Use Python Runner to run code in your browser — an online python code runner that works offline, no server, no account, no setup.

Python Runner – run Python code in your browser, offline and private Python Runner is a local code runner for Chrome: paste a snippet, press Run, read the output. The interpreter lives inside the extension, so your script never leaves your computer — no server, no account, no internet needed. Need to test five lines from a tutorial, a GitHub issue or a chat with an AI assistant, but there is no interpreter installed on this machine? Open the runner and it just works. 🔒 WHY A LOCAL RUNNER Most online python code runner sites do the same job on somebody else's server. This one is different: 🔒 Everything runs in your browser — nothing is uploaded 🔒 Works offline: on a plane, behind a corporate firewall, on a locked-down laptop 🔒 No sign-up, no login, no daily limit on runs 🔒 Nothing to install — no interpreter, no pip, no terminal ⚡ KEY FEATURES 1. Editor with syntax highlighting, line numbers and auto-indent 2. Run with one button or Ctrl+Enter; Stop halts even an infinite loop 3. Output streams live; errors show the real CPython traceback with matching line numbers 4. Stdin field for input(), so interactive scripts work as expected 5. Snippets saved on this device — reopen yesterday's script in one click 6. Right-click selected code on any page → "Run selected Python" 7. Light and dark theme 📋 RUN SELECTED CODE FROM ANY PAGE Select a snippet on Stack Overflow, GitHub or in the docs, right-click, pick the runner from the context menu — the python script runner opens in a tab and executes it at once, indentation intact. It is the fastest way to check whether an answer actually works before you paste it into your project. 👥 WHO IS IT FOR 👤 Students following a course who need a python playground that keeps up with the textbook 👤 Developers who want a quick python sandbox for a one-off check without opening an IDE 👤 Analysts testing a regex, a date calculation or a list comprehension 👤 Teachers showing output live in class, on any computer 🆚 RUNNER VS ONLINE TOOLS Searching the web for a place to run a quick script usually lands you on a site with ads, a queue and a login wall. Python Runner gives you the same type-and-see loop without any of that: your code stays on your machine and keeps running when the connection drops. ⚙️ HOW IT WORKS → The extension ships CPython 3 compiled to WebAssembly (Pyodide) — the real thing, not a subset → The full standard library is on board, from json and re to datetime and collections → The first launch takes a few seconds to warm up; after that every run starts instantly → Each run gets a clean namespace, so leftovers from the previous run never surprise you 🚫 HONEST LIMITS - numpy and pandas are built in, so you can run pandas online without installing anything; requests and other pip packages are not available - No network access from Python and no files that survive a restart - No graphics: matplotlib windows and turtle are out of scope If you need other pip packages, this is not the right tool yet. If you need a fast python program runner for plain scripts, it is exactly the right one. 🚀 GETTING STARTED 1️⃣ Install the extension and pin it to the toolbar 2️⃣ Click the icon and choose Open Python Runner 3️⃣ Type or paste your script and press Run 4️⃣ Save it as a snippet if you want it tomorrow ❓ FAQ 1. I have a .py file, but Python isn't installed on this computer — can I still run it? Yes. Open the file in any text viewer, copy its contents, paste them into the editor and press Run. The whole script runs inside the tab, and no interpreter has to be installed first. 2. Does it cost anything, or is there a cap on how much I can run? No and no. There's nothing to pay, no daily quota and no ads; everything described on this page is included. 3. Is it a REPL, where I type one line at a time? Not quite. It's closer to a small IDE than to a shell: you write or paste a whole script, press Run and read the output underneath. If a run gets stuck, Stop halts it. 4. Can I use it with a whole class? Yes. There's nothing to sign up for, so it's easy to hand to a room full of students, and since it doesn't depend on the school network, a flaky connection won't stop the lesson. 5. Do I need to be online to use it? No. Python Runner works the same with and without internet: it happens in a browser tab, and the browser is where it ends. Stop hunting for a working sandbox every time you need to run python online. Install Python Runner and keep a real interpreter one click away. Python is a trademark of the Python Software Foundation; this extension is an independent project and is not affiliated with the PSF.