Free play
Easy · Medium · Hard
Logic puzzles
Free online Sudoku
A little space for a clearer mind
Solve in your phone or desktop browser, without an account or download. Fill each row, column and 3×3 box with 1–9, without repeats.
Continue practice→
Daily challenge
Beijing time · Today and the previous 90 days
Teaching hint
Reading the explanation leaves the board unchanged. Apply it to make the move.
How to play
Fill each row, column and 3×3 box with 1–9, without repeats.
Select an empty cell, then enter a number.
1–9 to enter · Arrows to move · N for notes · Delete to erase · Ctrl/Cmd+Z to undo
Only duplicates are marked by default. Enable to mark incorrect answers too. No mistake limit.
Free play
Rated by solving techniques · Every puzzle has one solution
Your puzzle is saved. A new puzzle replaces this level’s practice slot; other levels and daily challenges are kept.
Switching saves progress. Resume practice at each level or any saved daily challenge.
- Easy: Naked single · Hidden single
- Medium: Locked candidates · Naked pair
- Hard: Hidden pair · Naked triple · X-Wing
Teaching hint
Reading the explanation leaves the board unchanged. Apply it to make the move.
This reveals an answer directly, without a logical deduction. You can undo it.
- Naked single: Only one candidate remains after excluding the digits in this cell’s row, column and box.
- Hidden single: This digit has only one possible position in the highlighted row, column or box.
- Locked candidates: All candidates for a digit in one unit lie within another unit, so remove it from the other cells of that second unit.
- Naked pair: Two cells in one unit contain only the same two candidates. Remove those digits from its other cells.
- Hidden pair: Two digits in one unit occur only in these two cells. Remove their other candidates.
- Naked triple: Three cells in one unit contain only three candidates between them. Remove those digits from its other cells.
- X-Wing: In two rows or columns, a digit occupies the same two positions. Remove it from other cells of the crossing units.
Daily challenge
Daily challenges use Beijing time and a fixed Medium puzzle for each date. Free play lets you start more puzzles.
Beijing time · Today and the previous 90 days
Switching saves progress. Resume practice at each level or any saved daily challenge.
Daily challenge →Statistics · This device
Progress and statistics stay on this device. If browser storage fails, a notice appears and you can keep playing.
- Best time
- Average time
- Completed without hints
- Recent completions
FAQ
Frequently asked questions
Daily challenge
Daily challenges use Beijing time and a fixed Medium puzzle for each date. Free play lets you start more puzzles. Beijing time · Today and the previous 90 days
New puzzle
Your puzzle is saved. A new puzzle replaces this level’s practice slot; other levels and daily challenges are kept.
Teaching hint
Reading the explanation leaves the board unchanged. Apply it to make the move. This reveals an answer directly, without a logical deduction. You can undo it.
Check against the solution
Only duplicates are marked by default. Enable to mark incorrect answers too. No mistake limit.
This device
Progress and statistics stay on this device. If browser storage fails, a notice appears and you can keep playing.
Ready to make the first move?
Continue practice