Sudoku Solver & Generator
Generate a fresh puzzle every time. Unlike AI chatbots, this Sudoku runs a deterministic backtracking solver in your browser for hints, so explanations come from real solving techniques, not hallucination. No signup, no ads, no daily limit, no watermark.
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Why This Sudoku Beats AI Chatbots
AI chatbots like ChatGPT or Claude cannot play Sudoku interactively. They cannot maintain a live board, validate moves in real-time, or generate valid graded puzzles. This tool runs a deterministic backtracking solver in your browser, so the "hint with logic" comes from real solving, not hallucination. And unlike Sudoku.com or other apps, we have no ads, no signup, no daily limit, no paywall, no analytics, and no tracking.
Features That Solve Real Problems
4 Difficulty Levels
Easy, Medium, Hard, Expert. Calibrated by Juhe's puzzle generator. Infinite puzzles, never repeats.
Hint with Logic Explanation
Get the next logical move with the technique used (naked single, hidden single, etc). No more random guessing.
Pencil Notes / Candidates
Track possible numbers in each cell. Auto-notes fills candidates for you. Toggle between notes and final answers.
Auto-check & Highlight
Errors are marked in red. Duplicates in row, column, or 3x3 box are highlighted when you type.
Daily Challenge
One puzzle per day, same worldwide. Beat your personal best. Track streaks in statistics.
100% Private
Puzzle generation API call only. Solving runs entirely in your browser. No analytics, no tracking, no login.
Print / Export
Print any puzzle to solve on paper. Perfect for teachers, parents, and offline play.
Multi-language UI
English and Chinese interfaces. More languages coming. AI cannot translate Sudoku rules correctly.
How to Play Sudoku
Sudoku is a logic puzzle. Fill the 9x9 grid so that every row, every column, and every 3x3 box contains the digits 1-9 exactly once. Some cells are pre-filled (the "givens"); your job is to figure out the rest using deduction, not guessing.
Beginner Strategy
Start with rows, columns, or 3x3 boxes that have the most pre-filled cells. Use the process of elimination: if a row already has 1-5, the missing cells can only be 6, 7, 8, or 9. If a 3x3 box already has 1, 4, 7, the missing cells can only be 2, 3, 5, 6, 8, 9. The pencil notes feature automates this for you.
Sudoku FAQ
Is this Sudoku really 100% free with no ads?
Yes. No signup, no ads, no paywall, no daily limit, no watermark, no analytics, no third-party trackers. The site is funded by the developer. Puzzles are generated by the Juhe Data API and all solving runs in your browser.
How are the difficulty levels calibrated?
Puzzles are pre-graded by the Juhe generator at four levels: Easy (40-45 givens, mostly naked singles), Medium (32-36 givens, includes hidden singles), Hard (28-32 givens, requires chains and pairs), and Expert (22-28 givens, requires advanced techniques).
How does the hint with logic explanation work?
The browser runs a backtracking solver that mimics how humans solve: it scans for naked singles, hidden singles, then pairs, then chains. The first move it would make is shown along with the technique name. The hint never just gives the answer without telling you why.
Can I play Sudoku offline?
Once a puzzle is loaded, you can disconnect from the internet and keep playing. The hint, undo, pencil notes, and timer all run in your browser. Only the initial puzzle fetch needs a network call.
Does the daily challenge change every day?
Yes. A new Expert-level puzzle is generated for the daily challenge every 24 hours based on the user's local date. Stats track your daily streak and best time.
Will my statistics be saved?
Yes, all stats (best times per difficulty, win count, streak, mistakes) are stored in your browser's local storage. Nothing is sent to any server. Clearing browser data will reset them.
Is this better than Sudoku.com?
Different trade-offs. Sudoku.com has more animations and social features but shows ads and tracks you. This Sudoku has zero ads, zero tracking, all 4 difficulty levels free, a unique daily challenge, and a hint system that explains the logic. If you value privacy and a clean experience, this is the better choice.