tool to create, solve and explore 9x9-sudoku puzzles. there are samples given to demonstrate solution strategies/rules/methods. other samples from public sources(some of them are well-known) can be used to explore how this solver works. new puzzles can be created according to selected rating level. a puzzle to be solved can be given as a query parameter in url address like
?s=..7.....9.8....3.7.2.1.9....9.2....5.6..35.74..2..68..9....4.5.4..65....2..89.... where numbers define givens and dots (or dashes or zeroes) define cells to be solved. to start with a partially-solved puzzle an unsolved cell can also be defined as a list of remaining candidates enclosed in parentheses like (2357).
the solve process takes only selected solution strategies into account. this makes it possible to analyse rating/difficulty level of puzzles. but it may also lead to unsolvable puzzles because of limited use of solution stategies. strategies may name a concrete solution method or a group of methods with similar concept (click on group will expand it).