Online Kakuro

Kakuro is a crossword built from arithmetic instead of words. The grid mixes white cells with black clue cells, and each clue cell carries a small diagonal slash: the number above the slash is the sum of the horizontal run of white cells to its right, and the number below it is the sum of the vertical run beneath it. Your job is to fill every white cell with a digit from 1 to 9 so each run adds up to its clue — with the crucial catch that no digit may repeat within a single run. The puzzle first appeared in Dell magazines in 1966 as Cross Sums, was adopted and renamed in Japan in the 1980s, and returned worldwide as Kakuro during the sudoku boom.

Every board here is playable free in the browser, on phone or desktop, with no account. There is one shared daily Kakuro — an 8 × 8 medium board, the same for every player, with a streak counter and a permanent archive of past dates — plus an unlimited library across five sizes, from 4 × 4 starters to 9 × 11 grids, each one machine-verified to have exactly one solution reachable by pure logic. Difficulty labels are earned, not guessed: a technique-replay grader solves every puzzle and records whether it needed only entry-level moves, medium bounding logic, or hard pair techniques.

What makes solving Kakuro click is combination knowledge: a clue of 16 across three cells can only be certain digit sets, and some clues — the famous "magic blocks" like 4-in-two or 24-in-three — have exactly one. This site builds that knowledge into the game: tap any clue and a live helper shows every combination that still fits the digits you have placed, with the remaining sum worked out for you. When you want the theory behind it, the full combination tables and strategy notes live on their own reference page, printable for solving on paper.