Nine for iPhone and iPad
Sudoku that asks for nothing.
No ads. No tracking. No accounts. No purchases. Nothing leaves your device. The app opens, you play sudoku, you close it.
- Free, forever
- No ads
- No internet, ever
- 21,000 puzzles on board
- iOS 18
The idea
A sudoku app that respects you, teaches you, and asks for nothing.
Most free sudoku apps are ad networks with a grid attached. Nine is the opposite: every tier is available at install, every puzzle is solvable by pure logic, and the app is structurally incapable of collecting anything about you because it never makes a network request.
Difficulty
Difficulty means what it says.
A puzzle's tier is decided by the hardest technique it requires. Not clue count, not solve time. A grindy Medium is thrown away rather than relabelled Hard, so the labels stay honest.
| Tier | In a sentence | What you'll need |
|---|---|---|
| Junior | Four rows, four numbers. | A 4×4 grid for children learning the game. Singles only. |
| Easy | Scan and fill. | Naked and hidden singles. |
| Medium | You'll need to eliminate. | Locked candidates, naked and hidden pairs. |
| Hard | Bring a pencil. | Triples, quads, X-Wing, Swordfish, Jellyfish, XY-Wing, XYZ-Wing, simple colouring. |
Every puzzle has exactly one solution and can be finished without guessing. Puzzles that would need trial and error are rejected, not shipped.
Features
Built to be played for years.
Hints that teach
A hint that fills a cell is a cheat. Nine's hints escalate through four steps: where to look, which technique applies, why it works in plain language, and only then the digit. The same solver that rated the puzzle drives every hint, so it never suggests a technique the tier didn't promise.
A daily challenge that forgives
One puzzle a day, easing from Easy on Monday to Hard at the weekend. The puzzle is drawn when you open it, so a skipped day never wastes one. A daily started before midnight keeps its board the next morning.
Tile packs
Play with numbers, nine colours, nine fruits, or nine emoji standing in for the digits. The rules and the hints are unchanged, and hints name whichever tiles you're using.
Pencil marks, undo, check
Per-cell candidate notes with optional auto-removal. Unlimited undo and redo. A rationed Check button that marks wrong entries against the solution and shows how many checks you have left.
Never lose a board
Every tier has its own save slot, plus one for the daily, so starting something new never evicts a half-finished game. Boards, pencil marks, and the timer survive a force quit and a restart.
Statistics and streaks
Completion rate, best and average times per tier, hints used, mistakes made, and your daily streak. All computed on your device from your own history. Never uploaded.
Accessibility from day one
Full VoiceOver labelling on every cell, Dynamic Type, a colour-blind-safe palette that never encodes meaning in hue alone, 44-point touch targets, and respect for Reduce Motion.
Light, dark, and yours
Warm paper tones in light mode and a true dark theme. Conflict flagging, peer highlighting, timer visibility, and haptics are each a single switch.
21,000 puzzles, in the box
The entire puzzle bank ships inside the app. There is no spinner, no "generating", and no daily cap. At a puzzle a day plus a few extra, that's two decades of play.
Privacy
Collects nothing. Verifiably.
Nine contains no networking code at all. No analytics, no crash reporting, no advertising identifiers, no permissions prompts, and no third-party SDKs beyond a local database library. Its App Store privacy label is "Data Not Collected" because there is nothing it could collect.
What you won't find
Deliberately left out.
No sign-in. No ads or interstitials. No upgrade screen. No leaderboards or sharing. No onboarding carousel. No notification prompt. No rating nag. Each of those would need a network, and Nine doesn't have one.
Details
Native, small, and honest.
| Platform | iPhone and iPad, iOS 18 or later. One app, one binary. |
|---|---|
| Price | Free. There is no paid version and there never will be. |
| Puzzles | 10,000 Easy · 6,000 Medium · 4,000 Hard · 1,000 Junior, each uniqueness-checked and rated by a 16-technique solver |
| Storage | A small local database on your device, included in your normal iCloud or computer backup |
| Network | None |