Sudoku for Every Skill Level: 4 Free Modes, No Sign-Up

Sudoku is a number puzzle on a 9×9 grid split into nine 3×3 blocks. The idea is simple enough to explain in one breath: every row, column and block must contain the digits 1 to 9, each exactly once. No vocabulary and no trivia, just logic, which is why kids and adults can sit down to the same puzzle. If you usually prefer words, crossword puzzles make a good change of pace, but sudoku is the one to pick when you want to switch off general knowledge and only think. You can play sudoku online free right here. The puzzle opens in your browser, so there is nothing to download and no account to make. Click an empty cell, then type a digit on your keyboard or tap it on the panel under the grid. Conflicting digits get highlighted when you slip, and your progress is saved automatically, so you can close the tab and come back later. New puzzles appear daily. Difficulty depends on how many cells start empty and which techniques you need, so we split the puzzles into four levels: Easy with 35 empty cells, good for beginners and warm-ups; Medium with 45, a mix of logic and speed; Hard with 52, for people who already know the basics; and Expert with 58, a real test for experienced solvers. If you are new, begin with the "naked single", a cell where only one digit fits. It is the simplest and most reliable trick there is. Next comes the "hidden pair": when two digits can go in only two cells of a row, column or block, every other candidate can be struck from those two cells. On harder grids, look for pointing digits: if a digit inside a block can only sit in one row or column, remove it from the rest of that line outside the block. Start at the level that matches your experience and move up once puzzles begin to feel quick.