Fill the 9×9 grid so every row, column, and 3×3 box contains the digits 1–9 exactly once. Given clues stay fixed. Use notes to track candidates, and request smart hints when you want a teaching nudge instead of an instant answer.
Start with naked and hidden singles, then look for pointing pairs and naked pairs before harder fish patterns. Utilnivo’s hint system walks these techniques step by step. Read more on the strategies page.
Yes. Play in your browser with no account or download required.
Yes. Active games, preferences, daily progress, and statistics are stored locally on this device.
Each local date has a deterministic puzzle per difficulty so everyone shares the same board for that day.