Sudoku in JavaScript
This is my sudoku puzzle generator and solver that I originally wrote in JavaScript and is the basis for my Sudoku Forever app for Android. The source code is available under a BSD license. The user interface is contained within this html page. The solver engine can be downloaded here. This is essentially the same solver used in Sudoku Forever albiet much older and not optimized very well. Feel free to use this code for whatever you want. A shout out is not necessary but always appreciated.

Desktop users may use a keyboard and mouse to enter numbers. Mobile users may use the keypad. Or if you are on the desktop and like clicking a lot, you may also use the keypad.

The rules are pretty simple, each row, column and 3x3 square must contain the numbers 1-9 with no duplicates.

Medium and Hard levels may take a few seconds to load.

Internet Explorer:
Internet Explorer may complain about the script taking too long and ask if you want to stop it. You may need to click No several times. I may fix this in a future version (but I doubt it).