PlayfuloSUDOKU

PUZZLE

Sudoku

Free online sudoku in your browser. Play the daily challenge or free easy/medium/hard puzzles. Notes, undo, and hints — no sign-up on desktop, tablet, or phone.

Daily sudoku

2026-11-03

    One shared puzzle per day (Korea time). No login — everyone gets the same board, and clearing it puts you on today’s leaderboard.

    Free play

    Pick a difficulty and play as many as you like.

    Sudoku guide

    What is this game?

    Playfulo Sudoku is free online sudoku in the browser. No sign-up — fill a 9×9 grid with digits 1–9 so every row, column, and 3×3 box contains each digit once.

    Daily sudoku is one shared puzzle per day (Korea time) — no login required. After you clear it, check your spot on the daily sudoku leaderboard and add a nickname; streak and best time stay in this browser. Free play offers easy, medium, and hard with notes, undo, and single-cell hints.

    The board and number pad scale for desktop, tablet, and phone. Conflicting digits highlight in red.

    How to play

    Fill empty cells so each row, each column, and each 3×3 box contains 1–9 exactly once. Pre-filled clue cells cannot be changed.

    • Never repeat a digit in the same row, column, or box. Conflicts appear in red.
    • Notes mode lets you mark candidate digits in empty cells. Placing a final digit clears that cell’s notes and removes the same digit from notes in its row, column, and box.
    • A hint fills the selected cell with the answer if it’s empty or wrong (otherwise another empty cell), with up to 3 hints per puzzle. Undo reverts your latest entry but doesn’t give hints back.
    • When every cell is filled with no conflicts, you clear the puzzle. Time and move count are shown.

    Controls

    • Tap an empty cell, then enter 1–9 with the number pad. On a keyboard, use digits, arrows, and Delete.
    • Turn on Notes to mark candidate digits in a cell. Erase clears the cell.
    • Use Hint to fill one correct cell (up to 3 per puzzle), and Undo to reverse your last entry.

    Strategy tips

    • Lock a cell when only one candidate remains, and scan rows, columns, and boxes for digits that fit only one place.
    • When a digit has only two or three possible cells in a box, mark them with notes to avoid mistakes.
    • If a conflict turns red, revisit that digit first, and save hints for when you are truly stuck.

    Difficulty differences

    Easy, medium, and hard are not AI settings — they differ by how many clue cells are pre-filled. Easy has more clues for beginners; medium adds blanks; hard is sparse. Daily sudoku uses medium-style clue density as one shared puzzle per day. Every puzzle is a standard unique-solution sudoku.

    Common beginner mistakes

    • Guessing many cells makes recovery hard — narrow candidates first.
    • Check the whole row, column, and box — not just one cell.
    • Staring at a stuck daily puzzle — it's the same all day, so use notes or a hint.

    Sudoku diagram — when only one digit fits

    A standard sudoku, almost filled. Only the bottom-right cell is empty, and 9 is the only digit missing from its row, column, and 3×3 box. Difficulty on Playfulo is not an AI opponent. It is how many clues are filled in at the start.

    Start

    One empty cell: check the row, the column, and the box

    The last row already holds 1 through 8. The last column and the bottom-right box have no 9 either, so 9 is the only candidate. The marked cell is the one to fill.

    Line 1 / 4

    Same cell: 9, or 8

    On the left, 9 is the only digit missing from the row, the column, and the box. On the right, 8 is written again and all three rules break.

    Fits

    9

    The digit missing from the last row, the last column, and the box is the same digit.

    Clash

    8

    The 8 in the row, the 8 in the column, and the 8 in the box are marked together. One overlap is enough to make the cell wrong.

    How difficulty works in Playfulo sudoku

    Sudoku has no move-picking AI. The difficulty name is how many cells are cleared when the puzzle is built, and every puzzle has one solution.

    • EasyMore clues, so a cell with only one digit appears early. A good first exercise is to scan one row and write the missing digit.
    • MediumMore blanks, so cells with only one candidate are harder to spot at a glance. Daily sudoku uses this density. Pencil in candidates, and when a digit is final, clear it from the notes in that row, column, and box.
    • HardStill fewer clues. The rules do not change. A hint fills one cell with the answer, at most three hints per puzzle.

    A finished standard sudoku with the bottom-right cell cleared. Counting that row, column, and 3×3 leaves only 9. Difficulty as a clue count is how Playfulo builds its puzzles.

    FAQ

    What are the sudoku rules?

    Fill a 9×9 grid so each row, column, and 3×3 box contains digits 1–9 once. Pre-filled numbers are clues and cannot be edited.

    What is daily sudoku?

    Daily sudoku is one shared puzzle per calendar day (Korea time). No login — everyone gets the same board. Clear time and streak are saved in this browser, and you can share a result text with friends.

    How does the daily sudoku leaderboard rank players?

    The daily sudoku leaderboard ranks players by fastest clear time, and only each player’s first clear of the day counts. Clears that used hints are still ranked, with the hint count shown next to the time. Enter a nickname (2–12 characters) after clearing to appear by name; otherwise you show as Anonymous. Only clears whose solution and solve time the server verifies are ranked.

    What is the difference between easy, medium, and hard sudoku?

    Harder levels start with fewer pre-filled clues and more empty cells. Easy is for beginners, medium for regular play, and hard for focused sessions. The daily puzzle uses medium-style clue density.

    What techniques solve a hard sudoku?

    Start with the basics: find cells with only one candidate (naked singles) and digits that fit in only one place in a row, column, or box (hidden singles). When those run out, use notes to spot naked pairs and pointing pairs. If a hard sudoku still stalls, try advanced patterns such as X-Wing, Swordfish, or XY-Wing — our advanced sudoku strategies guide explains each with grid examples.

    When do I fill a cell even though it still has several candidates?

    Look at the whole row, column, or box, not only the cell. If a digit can go in only one cell of that house, fill it even when the cell has other candidates. That is a hidden single. If a cell has only one candidate, fill that naked single immediately. If neither is true, leave a note and erase that digit from the other cells in the house before you look again.