Constraint
I made https://constraint.fyi/ after getting frustrated on some of the harder Clues by Sam (https://cluesbysam.com/) puzzles for which the color tags aren't enough to represent everything you need to track: whether suspects have the same or opposite status, overlapping relationships, cardinality constraints (e.g. "2 of these 5 are criminal"), hypothetical branches, or where a clue came from. I realized that all clues could be represented by Boolean formulas, allowing a solver to check whether my deductions and hypothetical scenarios were consistent without revealing the solution. Of course the same solver can solve for individual variables, but that takes too much of the fun out of the game, so I left that feature out.