JIRiSS (Information Retrieval based Software Search for Java) is a software exploration tool that uses an indexing engine based on an information retrieval method. JIRiSS is implemented as a plug-in for Eclipse and it allows the user to search Java source code for the implementation of concepts formulated as natural language queries. The results of the query are presented as a ranked list of software methods or classes, ordered by the similarity to the user query. In addition to that, JIRiSS includes other advanced features like automatically generated software vocabulary, advanced query formulation options including spell-checking as well as fragment-based search.