Sudoku Online is a free, browser-based Sudoku website built for people who want to play, learn, and improve without installing an app. The goal is simple: make Sudoku fast to start, clear to understand, and comfortable to use on desktop and mobile.
What you can do on Sudoku Online
You can play Classic Sudoku across six difficulty levels, from Easy to Extreme, or switch to Killer Sudoku for cage-based puzzles. The site also includes a Daily Challenge, Sudoku tournaments, leaderboards, personal statistics, and optional player accounts.
- Play immediately: most Sudoku games can be started without creating an account.
- Choose the right level: six Classic difficulty levels provide a clear path from beginner practice to advanced solving.
- Use practical solving tools: notes, candidates, undo/redo, checking, and hints are designed to support logical solving rather than random guessing.
- Practice consistently: daily challenges, streaks, history, and statistics help you see progress over time.
Learn Sudoku, not just play it
The game is only one part of the website. Our guides explain the rules, candidate notation, common beginner mistakes, pairs, locked candidates, X-Wing, Killer Sudoku combinations, and other techniques in a step-by-step format. If you are new to the puzzle, start with How to Play Sudoku. If you already know the rules and want a structured solving path, continue with Sudoku solving techniques.
How we approach the experience
We design the interface around the puzzle itself. Controls should be predictable, keyboard and touch input should both work, and the board should remain readable across screen sizes. Game states, saved progress, error recovery, and accessibility are tested as part of the same product rather than treated as separate extras.
We also separate gameplay pages, learning guides, competition pages, and editorial articles so each page has a clear purpose. New educational content is added through the Sudoku Blog and linked back to the most relevant game or guide.
Free access and optional accounts
You can use the core Sudoku experience without paying or registering. An account is optional and is used for features such as saved identity, progress, statistics, and competition-related data where those features are available. Guest play may use a browser identifier so submitted results can remain associated with the same guest session.
Languages and global access
Sudoku Online is designed for an international audience. English is the default version of the site, and additional language versions use separate URLs so players can switch languages without mixing multiple languages on one page.
Who publishes and reviews the content
Articles are published under the Sudoku Online publisher identity unless the site administrator explicitly provides a real public editor/team attribution. We do not create fictional expert profiles simply to make a page look more authoritative.
The public publisher is responsible for the final decision to publish, update, re-target, or correct site content. Editorial automation can assist with QA and planning, but it is not presented as an independent human expert.
Publishing, testing, accessibility, and corrections
Our Editorial Policy explains how guides and articles are scoped, reviewed, and updated. The How We Test Sudoku Puzzles page explains the puzzle-quality checks behind uniqueness, stored solutions, difficulty grading, and Killer cage validation. Our Accessibility page describes the product practices we use to make gameplay and navigation easier to operate across keyboard, touch, and assistive technology.
If you find a gameplay bug, an unclear explanation, an accessibility problem, or information that should be corrected, please use the Contact page. Editorial reports are handled under our Content Correction Policy.