Run Python in your browser

Confirm Python is running. Smallest possible example.

The one-liner that makes Python feel like Python.

Load, filter, group, aggregate. No CSV download needed.

Headless matplotlib via Pyodide — figure renders inline in the output panel.

Fit a line to noisy data in 5 lines.

Fetch GitHub's API with requests. Auto-installed via micropip.

Run three coroutines concurrently with asyncio.gather.

Real validation without writing __init__ by hand.

Pull structured data out of messy text.

Pure-stdlib CSV with DictReader / DictWriter. No pandas needed.

json.loads, json.dumps, custom default for dataclasses.

Memory-friendly streaming with yield and generator expressions.

with-statement support via class + via @contextmanager decorator.

Custom exception hierarchy, EAFP, exception chaining.

PEP 604 union types, TypedDict, Protocol — what mypy expects in 2026.

groupby, accumulate, pairwise, combinations — the lazy toolkit.

Real-world decorator patterns: logging wrapper, functools.cache, retry on failure.

Real database (in-memory) — no install. Create, insert, query, parameterise.

Padding, alignment, thousand separators, dates, debug syntax.

Default values, dict comprehensions, dict union (|), nested gets.

Real cleaning: parse dates, strip whitespace, fill missing, dedupe.

Convolve a 1-D signal with a moving-average kernel.

Capture groups in re.sub callbacks. Slugify a string.

@property + @setter pattern for invariant-protected attributes.