About
Hapax legomenon (Greek: ἅπαξ λεγόμενον) — a word that appears exactly once in the surviving record of a language. A thing said only once.
Every shuffle of a 52-card deck is its own hapax. The order you just produced has, almost certainly, never been produced before — and never will be again.
Why every shuffle is unique
The number of distinct orderings of a 52-card deck is 52 factorial — 52 × 51 × 50 × … × 1. About 8.07 × 10⁶⁷. A 68-digit number.
No physical process anywhere has produced enough random shuffles to make a repeat likely. Not in 13.8 billion years; not from every human who has ever lived. The space of possible orderings is simply too large.
How this site shuffles
Each shuffle runs in your browser. We use crypto.getRandomValues() — the cryptographic random source built into modern browsers — to drive an unbiased Fisher–Yates shuffle. Never Math.random().
The resulting permutation is sent to the server, verified to really be a permutation of the 52 cards, hashed with SHA-256, and given a 16-character URL drawn from the front of that hash. Sixteen hex characters is 64 bits — about 18 quintillion possible URLs. Enough that two real shuffles are extraordinarily unlikely to collide.
Acknowledgements
The shuffling-since-the-Big-Bang thought experiment and the equator-walking comparison both belong to a long oral tradition in math popularization — passed between professors, magicians, and writers for decades.
The visual language owes obvious debts to the small school of monospace minimalism: pudding.cool, the Stripe docs, the Linear changelog.