Soduku
on the Web

soduku
faq
techniques
on the web
origin

There are thousands of free puzzles available on a variety of sites on the internet along with useful Soduku guides and Soduku solvers.

A handy starting point is the original Sudoku.com which includes a good introduction to the game, a forum and some free puzzles. For lots and lots of free puzzles you can't go far wrong with Daily Sudoku.

If you'd like Sudoku with a big slice of humor you can't go far wrong with the hillarious Sudoku Grandmaster. A few other sites of note that are probably worth a visit are Sudokufun.com and web sudoku, both of which include free puzzles.