The open deck

How the decks draw

• Seventy-eight printed decks, numbered 1 to 78. The number on the box is the deck id. Deck 0 is the open deck nobody owns; its card is the public card at the front door.
• One seed a day, from Ethereum. The card for a date is Ethereum’s first block after midnight UTC on that date: its mixHash is the day’s seed. Nobody chooses it and nobody draws; anyone with the block header can recompute the card.
• Each deck draws its own card from the same seed. The seed and the deck number go through one hash; the result picks one of 78 cards and its orientation. Decks differ in their card, never in what a card is.
• The day is Tucson’s. The site’s day is the civil day in America/Phoenix (UTC−7, no daylight time). The block that fixes a date’s card is made about seven hours before that day begins in Tucson, so it exists whenever the day does.
• Before 27 September 2026 the open deck’s public card was drawn on the day by the machine with a recorded seed. Those days keep their record and say so. The printed decks’ cards for earlier dates follow the rule from Ethereum’s merge on (15 September 2022); before that no seed exists.
• Nothing here is interpreted. The page gives the card, the seed, and the block. What a card means is a reading, and readings are for the people in the room.

daySeed  = mixHash of the first Ethereum block with timestamp >= 00:00:00 UTC of the date
index    = keccak256(daySeed ++ uint256(deck)) mod 156
card     = index >> 1        (0 The Fool ... 21 The World, then Wands, Cups, Swords, Pentacles, Ace to King)
reversed = index & 1

Check any day: /api/today?verify=ethereum&date=YYYY-MM-DD&deck=0 · For agents