Logic Studio
Build boolean and predicate logic in the browser, with live truth tables, simplification, and a Z3 solver.
Logic Studio builds boolean and predicate expressions in a graph editor or a notebook, and keeps showing you what they mean while you edit: the truth table, a two-level minimization, a satisfying assignment, and a diff against a second expression.
Simplification uses Quine–McCluskey. Satisfiability and predicate work go to Z3 compiled to WebAssembly, so SAT and SMT queries are answered in the tab rather than on a server. Nothing typed into the editor leaves the browser, which is also why it wants a current browser with WebAssembly and SharedArrayBuffer support.
Around that there is branch and assignment coverage analysis, PNG and SVG export of a graph, and the usual light and dark themes.
Symbolic logic gets hard to hold in your head well before it gets hard for a computer. Keeping the expression, its table, its simplification, and a concrete solution on screen together is mostly a way of keeping the notation attached to the cases it actually describes.
Logic Studio is a promoted member of the Solves.ca family.