Sudoku

An encyclopedia entry describing the rules, history, strategies and variants of Sudoku. Notes that these are a type of "Latin square" which have been analyzed since ancient times.

Offers a tutorial for creating puzzles, a Java-based solver, and links to other resources. [English/Japanese]

Offers classic Sudoku and variants, as well as an online solver.

Offers five difficulty levels.For each sudoku ,You can print with normal and candidate mode.

Article by Paula Dear. Covers history in Japan and the UK and compares to the Rubik's cube craze of the 80s.

Site with a very large number of puzzles and variants (4x4...25x25, Multi 2, Multi 4, Samurai Sudoku, etc.). Beginner to expert, solving engine, training aids, and "app-like" user interface.

Solve Sudoku puzzles online, with interface targeted to tablets.

Sudoku generator/solver/analyzer written in Java/Swing (English and German). Lots of human style techniques (singles, subsets, LCs, fish, wings, uniqueness, coloring, chains, ALS), powerful analyzer (manage multiple solutions for one sudoku).

Sidokus are musical sudokus, with musical notes instead of numbers and a hidden melody.

3D Sudoku program for Windows and Mac. Easy puzzles are free, others cost money.

Many free puzzles playable online, in three sizes: 4x4, 6x6, and 8x8, in three difficulty levels. Also has "no-op" puzzles (where the operator clue is not given).

Puzzles playable online, sizes 3x3 to 9x9, as well as tutorials and tips.

Comprehensive site with Killer Sudoku puzzles, variants, and solving strategies.