 Le Goff, the abstraction and separate compilation formalized by O. Maffeïs, and the implementation of distributed programs developed by P. Aubry.The Polychrony toolset is an open-source development environment for critical/embedded systems based on SIGNAL, a real-time polychronous data-flow language.It provides a unified model-driven environment to perform design exploration by using top-down and bottom-up design methodologies formally supported by design model transformations from specification to implementation and from synchrony to asynchrony.