A friendly starting point

Nine digits.
One clear next step.

Fill every row, column, and 3 × 3 box with the digits 1 through 9, using each digit once. The starting numbers stay fixed.

Make your first move

Select an empty square, then tap a number below the board or type 1–9. Arrow keys move the selection. Use Backspace or Delete to clear a number you entered.

Think in pencil

Turn on Notes to record possible digits. Auto-marks fills candidates for you; Undo steps back through your changes. Notes are possibilities, not final answers.

Get a nudge

Open the hint panel when you are stuck. Follow the explanation before revealing more. For a deeper introduction, visit Bruce Dumes’s Sudoku guide.

Set your pace

The difficulty dial starts a new puzzle at the selected level. New puzzle gives you a fresh board; Restart returns to the beginning of your current puzzle. You can switch Classic, Quiet Ledger, or Nocturne styles without losing your moves.

Save and share

Your guest game saves in this browser. Use Share puzzle to send the same starting puzzle to a friend. Your private moves and account details are not in the link.

Sign in with an FCC account for cloud sync and My games history. SudokuDog keeps its own saved game, records, and history, separate from FCC Sudoku. Your account works on both, but playing here does not change your FCC game. Guest saves and website sign-in sessions do not automatically move between domains.

Take SudokuDog with you

iPhone or iPad: open this site in Safari, choose Share, then Add to Home Screen.

Android or desktop: use your browser’s Install app or Add to Home Screen option when available. You can also keep playing in a normal tab.

After the game has loaded online, its installed web edition can open offline for guest play. Sign-in, cloud history, and syncing need a connection. A saved game tied to an account stays protected until your identity can be checked online.

Need a hand?

Send feedback or report a problem. Include your browser and what happened, but never send a sign-in code.