The fc2tools set: a toolset for the verification of concurrent systems. The FC2Tools package, together with its graphical editor Autograph, is a forerunner amongst softwares dealing with model-based, automatic verification of distributed communicating systems. It is developed jointly by INRIA and Ecole des Mines/CMA as part of the MEIJE research team. Main features are: implementation of process algebra theory, for syntax and semantics; verification by compositional reductions and abstraction; alternative or combined use of explicit and implicit (BDD) implementation styles for better efficiency; use of specific FC2 file exchange format for easy interface with other verification softwares.