Sudoku Solver: Step-by-Step

Understand your next Sudoku move with candidate evidence you can inspect. Play classic and diagonal 9x9 Sudoku offline. Pay once to download; all features are included. No subscriptions, in-app purchases, ads, accounts or tracking. INSPECT THE REASONING Hints progressively reveal a target cell, technique names, recorded deductions and the next placement. Select a deduction to see its candidate snapshot on the board. Related cells are highlighted; removed candidates are crossed out. Each elimination lists the affected cell and candidates before and after it. These previews do not change your notes. The hint engine supports naked singles, hidden singles, naked pairs, hidden pairs, pointing candidates, box-line reduction and X-Wing. A hint may combine several eliminations before reaching a placement. It does not promise a human-style proof for every puzzle. When these techniques cannot derive a placement, the app labels the result as a solver answer reference and asks before showing that cell's answer. The separate Answer tool reveals the completed grid after confirmation, not a full solution walkthrough. LEARN AND PRACTICE Nine lessons each include a distinct explanation, a local candidate diagram, a revealable walkthrough and a multiple-choice exercise with feedback. Lessons cover singles, candidate checking, pairs, locked candidates, X-Wing and trial/backtracking. The diagrams are teaching examples, not complete playable puzzles. Open the matching lesson directly from a logical hint. PLAY YOUR WAY • Generate uniquely solvable classic or diagonal puzzles locally. • Browse the classic puzzle library in three level groups, with more puzzles loaded as you scroll. • Choose from five clue-based difficulty settings. • Try a daily puzzle, enter a classic puzzle manually or import a puzzle code. • Use notes, automatic candidates, undo/redo, optional error checking and a pauseable timer. • Keep local completion history, favorites and statistics; export and import a backup file. • Switch between English and Chinese, and between light, dark or system appearance. READ THE RULES The rule directory has 20 entries, including classic Sudoku, with specific rules, examples and common pitfalls. Only Classic and Diagonal are playable. Other entries are reading guides, not extra games or supported puzzle imports. Puzzles, progress and settings are stored locally. There is no account sync. Difficulty settings use starting clues rather than an official human-solving rating. This app is for entertainment and logic practice.