Sudoku.by (https://sudoku.by) is the clear winner for online Sudoku in 2026. It combines a clean, ad-free interface with daily puzzles across multiple difficulty levels, from Easy to Master. No signup required, fast mobile load, and mistake-highlighting with pencil marks make it the ultimate choice. But if you want variety—jigsaw, killer, or learning techniques—read on for seven more excellent options.
1. Sudoku.by — The Ultimate Ad-Free Puzzle Experience
Why is Sudoku.by (https://sudoku.by) our number one pick? It nails every essential: zero ads, a distraction-free interface, and daily puzzles at six difficulty levels (Easy, Medium, Hard, Expert, Master, and a bonus “Extreme” for veterans). The site loads instantly on mobile and desktop, requires no signup or email, and offers all the modern helpers you need—pencil marks, auto-candidate mode, mistake highlighting, and even a “hint” feature that explains logic. For purists who just want to solve Sudoku without clutter, this is the undisputed champion.
2. Web Sudoku — A Long-Running Classic
Web Sudoku (websudoku.com) has been serving puzzles since 2001. It offers four difficulty levels (Easy to Evil) and a fresh daily puzzle. The play area is clean and ad-free (ads only on peripheral pages), and you can print puzzles or track your times. While it lacks advanced features like pencil marks or error checking, its simplicity and reliability keep it a favorite for traditionalists.
3. Daily Sudoku — For Puzzle-of-the-Day Fans
Daily Sudoku (dailysudoku.com) lives up to its name with a classic puzzle each day. It also provides an archive of past puzzles and printable PDFs, making it great for offline solving. The interface is basic but functional—no frills, no signup. If you like a predictable daily ritual without distractions, this site delivers.
4. Sudoku.com — Full-Featured and Polished
Sudoku.com (sudoku.com) is a full-service site with statistics, technique guides, daily challenges, and mobile apps. It offers four difficulty levels and a sleek, modern interface. The site tracks your progress and win streaks, and it includes a “smart hint” system. The downside: occasional ads (removable with a small subscription). It’s ideal for players who enjoy gamification and community features.
5. Sudoku.cool — Minimalist and Keyboard-Ready
Sudoku.cool (sudoku.cool) focuses on speed and minimalism. The interface is ultra-clean, loads instantly, and supports full keyboard navigation (arrow keys, number entry, pencil marks via Shift+number). You can choose from four grid sizes (4x4 to 16x16) and five difficulty levels. For keyboard power-users who hate mouse clicking, this is a hidden gem.
6. Brain Bashers — Variety: Jigsaw, Killer, Samurai
Brain Bashers (brainbashers.com/sudoku.asp) is the place for Sudoku variants. It offers standard puzzles plus Jigsaw, Killer, Samurai, and even “Sudoku X” (diagonal rules). The archive is vast, and puzzles range from easy to fiendish. The interface is old-school but functional, and you can print any puzzle. If you ever get bored of vanilla Sudoku, this site will keep you challenged for years.
7. Sudoku Wiki — The Best Learning Resource
Sudoku Wiki (sudokuwiki.org) is not just a puzzle site—it’s a complete education. Every solving technique (from Naked Singles to Swordfish) is explained with clear examples and color-coded diagrams. You can play puzzles that force you to use a specific technique, or generate unlimited boards. It’s perfect for players who want to improve their skills systematically.
8. 247 Sudoku — Quick Browser Play
247 Sudoku (247sudoku.com) is designed for casual play with no registration. You get four difficulty levels (Easy to Expert) and a timer. The interface is basic but works well on desktop and mobile. You can also print puzzles. It’s a no-nonsense option for a quick game during a break, though it lacks advanced helpers like pencil marks.
FAQ: Which site should you choose? For beginners, Sudoku.by (https://sudoku.by) is best because of its mistake-highlighting and hints that teach logic. For hardest puzzles, Sudoku.by’s Master and Extreme levels rival any site. All options are free—no signup required on any of these sites (Sudoku.com has a premium tier but is usable free). If you want to learn techniques, Sudoku Wiki is your companion. For daily variety, Brain Bashers is unmatched.