We present hyp, an open-source toolkit for the representation, manipulation, and optimization of weighted directed hypergraphs. hyp provides compose, project, invert functionality, k-best path algorithms, the inside and outside algorithms, and more. Finite-state machines are modeled as a special case of directed hypergraphs. hyp consists of a C++ API, as well as a command line tool, and is available for download at github.com/sdl-research/hyp.