Sudoku online free
A live 9×9 grid, real difficulty bands, pencil marks, and hints that name the technique — free in your browser. No account.
Play instantly · No signup · Runs in your browser
The homepage
The grid is already live. No Play gate.
A lot of “free sudoku” tabs make you click Play, sit through a download nudge, or land inside a wall of unrelated game thumbnails before you see a single empty cell. Here the classic 9×9 opens with the page. Difficulty and the timer sit next to the title. Pencil, Check, Hint, New puzzle, and Daily sit under the board. If you only have four minutes before a meeting, you are already placing digits — no signup, no install package.
SudokuGridBase is one game on one domain. Progress — board, pencil marks, elapsed time — stays in this browser until you tap New puzzle. We are not an app-store listing, not a multiplayer lobby, and not a site that exists to dump every answer for every seed.
Why this tab exists: we kept hitting pages that bury the puzzle under ads or treat sudoku as one tile in a portal. So this homepage keeps the board first, puts short guides on the same domain, and makes Hint explain the move instead of flashing a silent digit.
Who shows up
Commute fillers, first-timers, stubborn hard bands.
Some people open a tab between calls and leave after a handful of fills. Others come back when they finally want to stop guessing and learn why a cell can only be a 7. Phone players tap; desktop players use keys. Same engine.
- Five quiet minutes. Open the tab, place a few digits, close it. No profile setup.
- Still learning the rules. Use the board above first, then skim the how-to guide for rows, columns, boxes, and first moves — that page keeps a live grid too.
- Want cages or a longer fight. Prefer sum cages? Try killer. Want fewer givens and slower thinking? Hard or evil bands. Named habits live in the strategy notes — see Modes and guides further down.
Rules
How a valid grid works
Fill every empty cell with a digit from 1 to 9 so that each row, each column, and each 3×3 box contains every digit exactly once. The darker “given” clues stay fixed — you cannot erase them. That is the whole classic rule set.
Harder labels are not different rules. Easy boards leave more givens and more naked singles. Hard and evil boards strip clues so you spend longer scanning units, marking candidates, and using patterns that go past “only one digit fits this cell.” If a page promises “extreme” but only reskins the same medium puzzle, that is not what the difficulty control here is doing.
Killer adds one more constraint: dashed cages show a sum. Digits inside a cage stay unique and must add to that sum, on top of the usual row, column, and box rules. Classic homepage play does not use cages; the Killer page does.
Controls
Pick a cell. Place a digit. Mark notes when you stall.
- Select. Click or tap an empty cell. Arrow keys move the selection on a keyboard. Related row, column, and box tint so you can see the unit you are scanning.
- Place. Type 1–9 or tap the pad under the board. The first fill starts the timer. Erase with Backspace, Delete, 0, or the Erase control. Givens never move.
- Pencil. Turn Pencil on to toggle candidate notes in a cell. Notes sit in a 3×3 layout inside the square. Turn Pencil off to commit a digit. If a cell already has your ink, penciling clears that ink so the notes stay readable.
- Check / Hint / New / Daily. Check highlights conflicts without dumping the full answer. Hint names a technique and marks the pattern. New puzzle deals another unique board for the current difficulty. Daily locks a calendar-day seed on this device so the same day returns the same puzzle.
Sound starts off every visit — mute by default so a quiet office does not get a surprise beep. Toggle it from the header (or the mobile action strip) after a gesture if you want feedback.
Technique hints
Hints that name the move — not a magic “solve” button
Plenty of sites slap “AI” on a button that fills a cell and never says why. Ours returns a technique label (naked single, hidden single, locked candidates, fish patterns when they apply, cage sum on Killer), a short English reason, and a highlight on the cells that matter. Place tips tell you which digit; elimination tips trim candidates from pencil marks when you have been noting them.
If you have an empty cell selected, Hint stays on that cell: either a move that involves it, or a candidate list when no named technique sits there yet. If you have a filled or given cell selected, Hint looks for the next useful move elsewhere on the board. Logic runs in your browser Worker — your grid is not uploaded for coaching.
Hint is a teaching nudge. On brutal bands it can miss ultra-advanced patterns or tell you there is no standard technique on the cell you picked. Check is the conflict flag, not a full solution dump. That split is intentional.
Modes and guides
Classic board here. Variants and reading one click away.
This page is the standard 9×9 with a medium default. When you want sum cages, open killer sudoku — same digit rules, extra cage sums, Hint that respects those cages. When you want fewer givens without changing the rule book, use hard sudoku or evil sudoku. Each of those pages keeps a playable board in the first fold.
Prefer reading before you fill? Start with how to play for rules and first moves, then sudoku strategy for habits and named techniques. Those pages are guides with a live board still on screen — not a blog that forgot the puzzle.
Boundaries
What you get — and what we skip
You get a playable classic grid on open, local progress in this browser, pencil marks, Check, technique-named Hint, Daily, and difficulty bands that actually change the puzzle. Ads — when they are enabled — sit under the action rail inside the first fold, never painted over the cells.
You do not get a multi-game portal, an unblocked-games directory, a printable bookstore, or a one-click “reveal every answer” product dressed up as the main CTA. School firewall workarounds are not the pitch; if someone only wants that, they will bounce, and that is fine.
Take breaks. Sudoku is a pastime, not a productivity metric. If a Hint feels wrong, Check the conflicts, erase a guess, or deal a New puzzle — the board is yours.
FAQ
Common questions
What is SudokuGridBase?
A free browser sudoku site. The 9×9 on the homepage is already playable when the tab opens. You get pencil marks, a Daily board, difficulty bands that change clue count, and a Hint that names the technique. It is not a store app, not a multi-game portal, and not a page that dumps full solutions as the main product.
Do I need to click Play first?
No. There is no Play gate. Select a cell, type or tap a digit, and the timer starts when you place something. Refresh keeps your in-progress board in this browser until you tap New puzzle.
Does it work on phone and desktop?
Yes. On a phone, tap a cell then use the number pad. On a desktop, click a cell and use keys 1–9, arrows to move, and Backspace or Delete to erase. Same rules either way.
Are the difficulty labels real?
Yes. Easy through extreme change how many givens stay on the board and how often you need techniques beyond naked singles. They are not six skins of one fixed puzzle with different titles.
Do hints upload my board?
No. Hint and Check run in a Web Worker inside your tab. We do not sync your grid to a coaching server or put you on a public account ladder.
What does Hint actually say?
A technique name (for example naked single, hidden single, or a cage sum on Killer pages), which cells matter, and a short English reason. Place hints tell you the digit; elimination hints trim candidates from your pencil marks when those notes exist. It can be wrong or incomplete on brutal boards — treat it as coaching, not a proof.
Where are Killer, hard, and evil modes?
On their own pages, with that mode already loaded in the first fold: killer cages, hard, and evil. Strategy notes and a how-to guide live next to them so you are not hunting a sitemap.
Are there other games on this domain?
No. One puzzle shape: classic sudoku and close variants. If you want 2048, Snake, or a thumbnail wall of unblocked games, that is a different site.
Can I download an app, use Flash, or buy a printable pack?
No download package and no Flash. Play in the browser. We are not a printable bookstore or PDF wholesale shop — if you need paper packs, look elsewhere.
Does Check reveal the full solution?
No. Check flags conflicting digits (and finished cage sums on Killer). It will not paint the entire answer grid as a one-click dump. When every cell is filled and conflicts are gone, you get a complete message.