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.

Seams word list

Seams uses the 12dicts word lists compiled by Alan Beale, released to the public domain. Thank you, Alan. Every Seams puzzle is checked by a solver against a 41,000-word dictionary, so it has exactly one full answer, and offensive words are filtered out.

Harbor boards

Harbor is a classic bridges logic puzzle (a public-domain puzzle type). We generate every board ourselves, and an exhaustive solver proves each Easy, Medium and Hard board has exactly one solution.

Privacy

Your stats and streak are saved only in this browser (localStorage). No account, no login. See the full privacy policy (required before ads).