About Stack

Stack is a free daily puzzle. Everyone gets the same five cards, and you have three tries to put them in order. A new puzzle comes out every day at midnight Pacific time.

Free forever

Every puzzle, including the whole archive, is free to play. There's no paywall, no trial, and no subscription. Ads keep the lights on, and an optional one-time "no ads" unlock is planned. It will never be needed to play.

Where the facts come from

Every value comes from Wikidata, whose structured data is public domain (CC0). Each value has to have a cited source on Wikidata, and it has to match the infobox of the English Wikipedia article. Population puzzles use 2020 U.S. Census counts. Anything where the two sources disagree gets left out. Neighboring answers always differ by at least 15%, so there are no near-ties. Every card links to its sources once the puzzle is over.

Spot a mistake? Fix it on Wikidata, and tell us.

Privacy

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