Feature modeling is a key technique used in product-line development to model commonalities and variabilities of productline members. In this paper, we present FeaturePlugin, a feature modeling plug-in for Eclipse. The tool supports cardinality-based feature modeling, specialization of feature diagrams, and configuration based on feature diagrams. Categories and Subject Descriptors D.2.1 [Software Engineering]: Requirements/Specifications— Tools; D.2.2 [Software Engineering]: Design Tools and Techniques—Computer-aided software engineering (CASE) General Terms Design Keywords Configuration, domain analysis, software-product lines, software reuse, system families, variability modeling and management