Features
What is in the app, in one place.
Learn
Two dozen techniques
From Naked and Hidden Singles through pairs, triples and quads, to X-Wing, Swordfish, Jellyfish, wings, Skyscraper, XY-Chains and Unique Rectangles.
Hints in steps
Where? → Which cells? → Why? → Apply. Ask for only as much as you need.
Practice mode
Pick a technique and solve a puzzle that needs it, with a badge showing which technique you are practising.
Written explanations
Every technique has a full explanation with diagrams. Reading is always free.
Step by step
Follow a reasoning chain one link at a time, forwards or backwards.
One highlight language
Solid outline for evidence, dashed outline and strikethrough for eliminations — the same for every technique.
Play
Five difficulty levels
Easy, Medium, Hard, Expert and Master, from a large bank of puzzles graded by the techniques they require.
Your own notes or automatic
Snyder-style notes in amber, automatic candidates in grey. Use either or both.
Enter your own puzzle
Type or paste in a puzzle from anywhere and get the same hints and tools.
Multi-select
Drag across cells and enter a number or candidate in all of them at once.
Undo and redo
Take a move back, or forward again.
Mistake checking
Wrong numbers are counted, so you can see how clean a solve was.
Comfort
Larger numbers
One setting makes both digits and candidates bigger, for easier reading.
Row, column and box highlighting
Switch on a gentle highlight of the selected cell’s peers, or off for a clean grid.
Light and dark
Follows your device, or choose one.
Works offline
Puzzles, hints and explanations all run on your device.
Progress and privacy
Statistics
Time, mistakes, hints used, and which techniques you found yourself versus with a hint.
Personal bests and streaks
Tracked automatically, no set-up.
No account, no ads, no tracking
Your progress stays on your device. Only subscription purchases involve Apple and RevenueCat — see the Privacy Policy.
Free and Premium
Grid9 is free to download and play. Premium is an auto-renewing subscription (monthly or yearly) that unlocks the deeper learning tools. Eligible new subscribers get a free trial. Prices are shown in the app in your local currency before you subscribe, and you can cancel any time in your iPhone’s settings.
| Free | Premium | |
|---|---|---|
| Play puzzles, notes, undo/redo, statistics | ✓ | ✓ |
| Read the explanation of every technique | ✓ | ✓ |
| Hint overview: which techniques have a hit, and how many | ✓ | ✓ |
| Larger numbers, highlighting, light/dark | ✓ | ✓ |
| Full hint walkthroughs (Where, Which cells, Why, Apply) | ✓ | |
| Practise a technique on real puzzles, with Step by step | ✓ | |
| Enter and solve your own puzzles | ✓ |
Subscription details are in the Terms of Use.
Coming soon to the App Store