Kodkod is an efficient SAT-based constraint solver for first order logic with relations, transitive closure, bit-vector arithmetic, and partial models. It provides automated reasoning facilities for both satisfiable and unsatisfiable problems: a finite model finder for the former and a minimal unsatisfiable core extractor for the latter. Kodkod is used in a wide range of applications, including code checking, test-case generation, declarative execution, declarative configuration, and lightweight analysis of Alloy, UML, and Isabelle/HOL.
Designed as a plugin component that can be easily incorporated into other tools, Kodkod provides a clean Java interface for constructing, manipulating, and solving constraints. The implementation is open-source and available for download under the MIT license. The source code is extensively documented, and the distribution includes many examples demonstrating the use of the Kodkod API.