Open reference
Free reference material, no app required
Every app here sits on top of a body of knowledge. We publish that knowledge openly — no paywall, no sign-in. If it happens to answer your question, the app is right there.
Birthday Archive
Who died on each day of the year — curated from 569,000 Wikidata records, with sources.
Full rulesetTianjin mahjong scoring
The fan table and scoring rules in English and Japanese. Almost nowhere else has this.
6 calculatorsElectronics bench reference
Resistor colour codes, trace width, voltage drop, dividers — with the formulas and their sources.
From the apps
Each app below rests on a body of knowledge: painting manuals, seal-carving, astronomy, jazz harmony. These are the parts worth reading on their own.
The seven texture strokes (cun) of Chinese landscape painting
Hemp-fibre to Mi dots: what each texture stroke looks like, who used it, and the numbers behind it.
A Thousand LiGuo Xi's three distances: high, deep and level
High, deep and level distance: Guo Xi's words, and what each one does to a landscape.
Four Treasures of the StudyHow to read a Chinese seal
Red or white characters, where to start, and what kind of seal you are looking at.
Four Treasures of the StudyThe Four Treasures of the Study: brush, ink, paper, inkstone
Brush, ink, paper, inkstone, and what actually differs between their kinds.
Four Treasures of the StudyMiaohong: how to practise with a red tracing copybook
Red models, the 米 grid, outline tracing, and why the first character is 永.
One LightHow far has light travelled since a given day?
Pick a date: how far light has gone since, from the Moon to Sirius. With a calculator.
One LightSirius, the Dog Star — and the cat that was erased from the sky
Why Sirius is the Dog Star, how far it is, and the cat constellation that was erased.
Infinite LoungeWhat is a jazz piano trio? Who plays what, and who listens
What piano, bass and drums each do, how swing changes with tempo, and why they listen.
Infinite LoungeThe ii–V–I progression: a practical introduction
Chord names, the rootless voicings that make it glide, and where it appears.