Choose your pace
Expert: expert puzzles
Expert puzzles that need Swordfish, W-Wings, coloring and unique rectangles. If you are stuck, a hint walks through the exact pattern on your board.
Techniques you will meet: Swordfish, Jellyfish, Turbot fish, XYZ-Wing, W-Wing, Finned X-Wing, Sashimi X-Wing, Remote pairs, Simple coloring: trap, Simple coloring: wrap, Unique rectangle: type 1, Unique rectangle: type 2, Unique rectangle: type 4, BUG+1.
- CalmEasy. The two basic moves are enough.
- SteadyMedium. Pencil marks, pointing and pairs.
- FocusedHard. Triples and quads.
- TrickyVery hard. X-Wings, Skyscrapers, XY-Wings.
- ExpertExpert. Swordfish, coloring, rectangles.
- FierceEvil. Chains and almost locked sets.
Or play today’s daily puzzle: the same grid for everyone, calm on Monday and fierce by Saturday.
Hints
Hints that teach the move
Most apps just fill in a number. A SudokuByte hint shows where to look, explains why the move has to be true, and lets you try it on your own board. Only then does it make the change.
After a few, you start spotting the patterns yourself.
Lessons
Every technique, explained
8 short lessons on the basics and 56 techniques, each with a worked example from the same solver that rates the puzzles. Free, and checked.
- Hidden singleOne digit has just one remaining location in a house, even if that cell has several pencil marks.
- Naked pair2 cells in one house contain only 2 different candidates between them. They reserve those digits, in some order.
- Pointing pairA box needs a digit, and its only two possible locations are on one line. That line cannot contain the digit anywhere outside the box.
- X-Wing2 base rows confine a digit to 2 cover columns (or transpose rows and columns). Those columns are reserved for the bases.
- XY-Wing / Y-WingA two-candidate pivot XY sees wings XZ and YZ. One wing must be Z, whichever value the pivot takes.
- Swordfish3 base rows confine a digit to 3 cover columns (or transpose rows and columns). Those columns are reserved for the bases.
The tutor
Ask the tutor why
Sign in and ask about the board in front of you: why a move works, what to look for next, or just a nudge. The tutor sees your pencil marks and never gives the answer away unless you ask.
The tutor is the one paid part of SudokuByte, a small subscription from the iPhone app, because every answer has a real AI cost. Sign in here with the same account and it works on the web too.
Why can’t r5c3 be a 4?
Look along row 5: there is already a 4 in r5c8, and a row holds each digit once. So 4 is out for r5c3. Which digits are left for that cell?
Just 2 and 7.
Right. Now check its box. Only one of those still fits there.
On iPhone
On your iPhone, too
The same puzzles, lessons and progress. Sign in and your games follow you between the app and the web. Share a puzzle, and a friend can play the same grid here, no app needed.
Coming soon to the App Store
A note from Justin
Why I made SudokuByte
I love Sudoku, but the apps I tried were clunky, expensive or buried in ads, and none of them made it easy to learn from the puzzle in front of you. So I made SudokuByte: a calm place to play, where hints and lessons teach the logic one technique at a time.
Every puzzle, lesson and hint is free, and there will never be ads. If you would like to support the project, the iPhone app has a tip jar, or just tell a friend.
Justin, ByteSize Data Solutions
Questions
Good to know
Is SudokuByte really free?
Yes. Every puzzle, lesson and hint is free, with no ads, ever. The one optional paid part is the AI tutor in the iPhone app, because each answer it writes has a real AI cost.
Why are there no ads?
Ads make it hard to focus on a puzzle, and a calm place to play is the whole point. SudokuByte is supported by people who choose to tip or subscribe to the tutor.
How is difficulty rated?
The app’s solver works through each puzzle the way a person would and adds up how hard every step is. That gives a rating from 1 to 1000, grouped into six levels: Calm, Steady, Focused, Tricky, Expert and Fierce.
Do the puzzles need guessing?
No. Every puzzle has exactly one solution and can be solved with logic alone. The hardest levels use advanced patterns, and the lessons teach each of them.
How do hints work?
A hint does not just fill in a number. It shows where to look, explains why the move must be true, lets you try it on the board, and then applies only the proven change.
Do I need an account?
No. You can play every puzzle as a guest, and your games stay on your device. An account syncs your games across devices and unlocks ranked play and leaderboards.
Is there an app?
Yes. The SudokuByte iPhone app is on its way to the App Store, with the same puzzles, lessons and progress.