This paper presents the new version of Xfuzzy, Xfuzzy 3.0, which is a development environment for fuzzy-inference-based systems. It is composed by many tools that cover the different stages of the fuzzy system design process, from their initial description to the final implementation. Its main features are the capability for developing complex systems, the flexibility of allowing the user to extend the set of available functions and the possibility of been executed on any platform with JRE (Java Runtime Environment) installed.This work has been partially supported by the Spanish CICYT Project TIC98-0869 and the FEDER Project Nº 1FD97-0956-C3-02.Peer reviewed