Pro Subscription
Unlock advanced solving techniques and productivity tools to take your Sudoku skills to the next level.
Features
Smart Keyboard
Smart Keyboard filters available digits based on your current cell selection. Only valid candidates are shown, making input faster and reducing errors.
Persistent Focus Overlay
Persistent Focus Overlay keeps your focus highlighting visible even when navigating between cells, helping you maintain context while solving.
Auto-Highlighting
- Auto-highlight Hidden Singles — Automatically highlights cells where only one candidate is possible within a unit.
- Auto-highlight Bi-value Cells — Highlights cells with exactly two candidates, useful for finding chains and wings.
Techniques
Pro unlocks a comprehensive set of intermediate and advanced solving techniques:
Fish Patterns
- Swordfish — A 3-row/3-column fish pattern
- Jellyfish — A 4-row/4-column fish pattern
- Squirmbag — A 5-row/5-column fish pattern
- Whale — A 6-row/6-column fish pattern
- Leviathan — A 7-row/7-column fish pattern
Finned Fish
- Finned X-Wing — X-Wing with an extra candidate (fin)
- Finned Swordfish — Swordfish with fins
- Finned Jellyfish — Jellyfish with fins
Wings
Uniqueness Techniques
- Unique Rectangle Type 2 — UR with extra candidate in two corners
- Avoidable Rectangle — UR pattern with solved cells
- Hidden Unique Rectangle — UR with hidden candidates
- Extended Unique Rectangle — UR with additional cells
- Rectangle Elimination — Eliminations based on UR patterns
- BUG — Bi-value Universal Grave
Chaining Techniques
- X-Cycles — Single-digit chains with alternating strong/weak links
- XY-Chains — Multi-digit chains through bi-value cells
- 3D Medusa — Multi-digit colouring across the grid
- Alternating Inference Chains — Generalised chains with any link types
Exotic Techniques
- Almost Locked Sets — Sets with one extra candidate
- Aligned Pair Exclusion — Eliminations from aligned pairs
- Gurth's Theorem — Symmetry-based eliminations