Moose is a reverse engineering tool that uses multiple techniques like visualization, metrics, and semantic analysis to provide high-level views of large software systems. It integrates these techniques and allows querying and navigating codebases. Moose is language independent and has been used on real-world systems written in languages like Smalltalk, Java, C++ ranging from thousands to millions of lines of code. It is an extensible, collaborative environment for software reengineering.