Gooby
Works offline
All 1,200 puzzles are stored on your phone after the first visit. Play on a plane, in the subway, anywhere.
Free · Offline · No ads
Free Sudoku that works offline — and never shows an ad
1,200 hand-graded puzzles from Easy to Extreme, on your phone or computer. Hints teach you the technique instead of just filling a number. No account, no tracking, nothing to buy.
How to play Sudoku
Sudoku is a 9×9 grid split into nine 3×3 boxes. Some cells start with a number — the givens. Your job is to fill the rest.
- Every row holds each digit 1–9 exactly once.
- Every column holds each digit 1–9 exactly once.
- Every 3×3 box holds each digit 1–9 exactly once.
That's all. No maths is involved — the digits are just symbols. Every puzzle here has exactly one solution, so you never need to guess: there is always a logical next step. When you're stuck, a hint shows you where to look and names the technique.
Controls
- Tap a cell, then a number to fill it — or pick a number first and tap cells to place it again and again.
- Notes (pencil marks) record the digits a cell could still be. Turn on notes-first in the game settings if you like to note before you commit; a long press on a number then places it as the answer.
- Undo and redo any move, Erase a cell, or ask for a Hint (three per game).
- Placing a number can clear that digit from the notes in the same row, column and box automatically.
Six levels, graded by technique
Most apps grade Sudoku by how many numbers are given. We grade each puzzle by the hardest technique a person needs to solve it, so the levels feel consistent. Win a few games at one level to unlock the next.
| Level | What it takes |
|---|---|
| Easy | Hidden and naked singles, with plenty of givens. Perfect for learning. |
| Medium | Singles with fewer givens, plus pointing, box/line reduction and naked pairs. |
| Hard | Hidden pairs and triples. |
| Expert | X-Wing, XY-Wing and quads. |
| Master | Swordfish and XYZ-Wing. |
| Extreme | Beyond the standard techniques — for when Master feels easy. |
Each level has 200 puzzles. Finish one fast, with no hints and at most one mistake, to earn three stars. Learn every technique, step by step →
Why play Sudoku here
A calm, fast Sudoku that respects you — built as a web app, so it installs in seconds and works without signal.
No ads, ever
No banners, no videos for hints, no purchases. Every level is free.
Hints that teach
A hint first points at the cells and names the technique; only then can you apply it. You get better, not just unstuck.
Never lose progress
Every move is saved instantly. Close the app mid-game and pick up exactly where you left off.
Sudoku tips for beginners
- Scan the boxes first. Pick a digit and look for a box where it fits in only one cell — a hidden single. Most easy puzzles fall to this alone.
- Work on the busiest areas. Rows, columns and boxes with the most givens have the fewest options left.
- Use notes once singles run out. Writing candidates reveals pairs and pointing patterns you can't see otherwise.
- Never guess. Every puzzle has one solution reachable by logic. If you're stuck, ask for a hint and learn the pattern it shows.
Sudoku questions
Can I play Sudoku offline?
Yes. Open the game once and every puzzle is saved on your device. Add it to your home screen and it works with no connection, even in airplane mode.
Is this Sudoku really free, with no ads?
Yes. All six levels and every puzzle are free. There are no ads, no in-app purchases and no paid hints.
Does every puzzle have one solution?
Yes. Every puzzle is checked by a solver to have exactly one solution, and graded by the hardest technique a person needs to solve it without guessing.
What is the hardest Sudoku level?
Extreme. Its puzzles need more than the standard techniques (beyond Swordfish and XYZ-Wing), so they suit experienced solvers.
Do I need to download an app?
No. It runs in your browser. On iPhone use Share → Add to Home Screen in Safari; on Android use Install app in Chrome. It then opens full screen like any app. See the install guide.