Python Runner

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 for an online python compiler, a python interpreter or an online python ide usually lands you on a website with ads, a queue and a login wall. This extension gives you the same type-and-see loop as an online python runner, but as a python executor that lives on your machine — python runner online-style convenience, minus the upload. ⚙️ HOW IT WORKS → The extension ships CPython 3 compiled to WebAssembly (Pyodide) — the real thing, not a subset → Full standard library: json, re, itertools, datetime, math, collections, csv and more → 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 - Only the standard library: numpy, pandas, 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 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. How to execute .py online without installing anything? Open the .py file in any text viewer, copy its contents, paste them into the editor and press Run. Same result as typing "py online" into a search box, without a website in the middle. 2. Is it a free python code runner? Yes. Every feature described here is free, and the python code runner free of ads and tracking is the whole point. 3. Is it a python shell or a python console? It is closer to a python ide online than to a REPL: you run a whole script, not one line at a time, and you read the output below the editor. 4. Can I use it as a python coding runner for a class? Yes — a python online runner that needs no account is easy to hand to a room full of students. It is a free code runner Python teachers can rely on, because it does not depend on the school network. 5. Is there a python code runner online mode? 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.