Puzzle Tools
Free tools for mechanical puzzles. They run entirely in your browser, nothing is uploaded, and none of them need an account.
N-ary Puzzle Calculator
Snake Cube Solver
Soma Cube Shapes
Pentomino Solver
Polycube Box Fitter
6-Piece Burr Solver
Point at one to see what it does.
More are on the way. If there is a puzzle you would like a tool for, the blog is where most of them start. If you would rather play than solve, there are puzzle games too.