Play sudoku online, free, no account needed
What this is
Sudoku24x7 is a free sudoku site built around one idea: the puzzle should be the whole point, and everything else should get out of the way. No login, no popups, no ad-gated "second chance" after a few mistakes — just a board, five difficulty levels graded by the logic they actually require, and hints that explain the technique instead of just dropping in the answer.
Every puzzle is generated by our own code and checked to have exactly one solution before it's ever shown to you. If you want to see how a puzzle is meant to be solved step by step, the solver on /solver/ will walk through it.
How to play, briefly
Click or tap a cell, then type a digit (or tap it on the number pad below the board). Press N or the pencil icon to switch to notes mode for jotting down candidates instead of filling the cell. Arrow keys move the selection, Backspace erases, and Ctrl+Z undoes. A full walkthrough lives on /how-to-play/.
Choose your level
Easy
Naked and hidden singles only. A calm start, or a way to teach someone.
Medium
Adds locked candidates — the first technique that looks at a box and a line together.
Hard
Naked and hidden pairs, sometimes triples. You start tracking relationships, not just single answers.
Expert
Built around X-Wing — a pattern spanning two whole rows or columns at once.
Evil
XY-Wing, Swordfish, and whatever a puzzle needs beyond the techniques most solvers ever learn.
FAQ
Is this actually free, with no account?
Yes. Everything plays in your browser — progress, settings, and stats are saved with your browser's local storage, not an account. Nothing is sent anywhere to save your game.
How are the puzzles generated?
Our own code generates every puzzle from a random starting grid, removing clues while checking after each removal that exactly one solution still exists. Difficulty is graded afterward by running a logical solver and recording the hardest technique it actually needed — not by counting how many clues are left.
What happens when I make a mistake?
Depends on your settings. By default we highlight conflicting digits so you can see the problem, but you can turn that off, or turn on checking against the solution, in Settings. There's no forced game-over after a fixed number of mistakes.
Does it work on my phone?
Yes — the board, number pad, and controls are sized for touch, and the whole site works on a slow connection. There's also a printable version if you'd rather solve on paper.
Is it accessible with a keyboard or screen reader?
The board supports full keyboard play (arrow keys to move, number keys to enter, N for notes, Ctrl+Z to undo), and every cell is announced with its row, column, and value. We treat this as a feature, not an afterthought.