Run Python, JavaScript and TypeScript in any page

A code editor that actually runs the code it shows, as one custom element. No backend, no iframe, no sign-up — it all happens in the reader's own browser. Type in the box and press Run.

Python · JavaScript · TypeScript Real CPython 3.14 via Pyodide — full standard library, input(), tracebacks, numpy on demand — plus the browser's own JavaScript engine, and TypeScript with its types stripped. Each language loads only on the pages that use it.

name = input("what's your name? ") for i in range(1, 4): print(f"{i}. hello {name}") sum(n * n for n in range(1, 11))

That snippet blocks on input() — the program waits for you, the way a terminal does. No cross-origin isolation required.

One runtime per page

Every widget on a page shares a single Web Worker and a single Python runtime. Ten editors cost one ~11MB download, not ten.

See two editors share a worker →

Real modules and packages

A widget can hold a whole small project — flat modules, packages with __init__.py, data files you open(). Tracebacks name the real file and line.

See a package in a widget →

Runaway code can't freeze the page

Python runs in a Worker, so while True: is a stoppable mistake rather than a dead tab.

Try stopping an infinite loop →

Lessons that keep their place

Edits persist in IndexedDB, and soft navigation keeps the runtime warm between pages — the first run on a new lesson takes milliseconds, not seconds.

Walk between two lessons →

Add it to a page

One script tag. CodeMirror is bundled; Python is fetched at runtime.

<script type="module"
  src="https://cdn.jsdelivr.net/npm/code-playpad@0.1.3"></script>

<code-playpad height="180">
  print("hello from a CDN")
</code-playpad>

Or install it and use the modular build, with CodeMirror as a peer dependency so you never end up with two copies:

npm install code-playpad

React wrapper included — see it here. Works in plain HTML, Astro, Next.js, and anything else that can render an element.