Play Sudoku Online Free — No Download

How to Play

1. Choose a level: Easy, Medium, Hard or Expert. The clock starts as soon as the grid appears.
2. Tap an empty square to select it. Its row, column and 3×3 box light up so you can scan them quickly.
3. Tap a number on the pad (or type 1 to 9) to write it in. Tap the same number again, or press Erase, to clear it.
4. Switch on Notes to jot small pencil marks for the digits a square might hold.
5. Fill every square correctly to finish. Your time is your score, so faster is better.

Rules

Every row, every column and every one of the nine 3×3 boxes must contain the digits 1 to 9 exactly once. The dark digits at the start are clues and cannot be changed. Each puzzle is built by the computer and checked with a solver, so it always has one and only one correct answer that you can reach with logic alone — no guessing needed.

If you place a digit that repeats inside a row, column or box, both clashing digits turn red with a wavy underline. The game does not tell you when a digit is merely wrong, so careful thinking still matters. You get three free hints per puzzle; each one fills in a correct digit, picking your selected square when it needs fixing.

Tips & Strategy

• Hunt for hidden singles. Pick a digit, then check one box at a time. If only one square in that box can take the digit, it must go there — even when that square has other options.
• Use the highlight to count. Tap a placed digit and every copy of it glows. The rows and columns they cover show you at a glance where that digit can no longer go.
• Look for naked pairs. If two squares in a row can only be 4 or 7, those two digits are taken. Remove 4 and 7 from the notes of every other square in that row.
• Note the tight spots only. Writing notes in all 81 squares wastes time. Mark squares with two or three options, and let placed digits clean up the notes for you.
• Work on the busiest area first. Rows, columns and boxes that already hold six or seven digits have the fewest possibilities and usually break open fastest.

Game Modes

There are four levels. Easy leaves around 40 clues, so almost every step can be found by scanning. Medium removes more clues and asks you to use notes. Hard and Expert strip the grid down to the high twenties and mid-twenties, where pairs and careful elimination become essential.

The Daily Challenge is a Medium puzzle that is the same for everyone on a given day. Solve it to keep your streak alive, then share your time and level with a spoiler-free result line.

Play with Friends

This is a solo puzzle, but it works beautifully as a race. Pick the daily puzzle, agree on a start time with your friends or family, and compare finishing times when everyone is done. Tap Share on the result screen to post your time on WhatsApp or Telegram without giving away a single digit of the answer.