Everything in the catalog

Executes ES5-style JavaScript in a small WebAssembly engine and keeps the code in the page address.

A Minesweeper clone with three difficulty levels, flagging, a timer and long-press support on phones.

Five guided NumPy exercises plus a free playground, all running Python in the page through Pyodide.

Runs pandas, numpy and matplotlib in the browser via Pyodide to draw a bar chart.

Encrypts a message with a passphrase using browser crypto and produces a link that only decrypts with that passphrase.

Blurs faces and strips metadata from a photo locally, then saves a clean copy.

Removes comments from Python code using the real tokenizer on Pyodide, leaving strings and docstrings intact.

An interactive Python prompt running on Pyodide with several runtime versions and command history.

Runs JavaScript inside a QuickJS WebAssembly sandbox with a synchronous fetch helper and example snippets.

Runs the Redis AR* array commands against an in-memory instance compiled to WebAssembly.

Counts source lines by language from pasted code, a GitHub repo or a ZIP and estimates effort with COCOMO.

Parses SQLite SELECT queries into an abstract syntax tree shown as JSON and Python.

Shows the VDBE bytecode SQLite generates for a query, using EXPLAIN.

Runs SQLite in WebAssembly and shows query results in about twenty formats including boxes, CSV, JSON and Markdown.

Runs a query in browser-based Python SQLite and annotates EXPLAIN and query plan output in plain English.

Formats, parses, validates and tokenizes SQLite SQL in the browser using a compiled parser.

Re-encode a video with FFmpeg compiled to WebAssembly, producing several quality variants to compare and download.

Mobile timing app that lays out when to start each step to cook two meals at once, with a start button and countdowns.