SnapSolve was inspired by Sudoku Grab, an app that scans sudoku's to solve them. SnapSolve does more or less the same, but with Boggle/Ruzzle instead of sudoku's. For the image processing, it uses OpenCV (see its license).
Originally, it was written for Boggle, but during development the game Ruzzle appeared. And of course, SnapSolve works with Ruzzle as well. It even supports the score modifiers. Because the letter recognition is generic, it also works with various other Boggle clones, like Wurdle, Quordy and Word Jam.
I wrote a blog about the inner workings of SnapSolve.