Repo-scan is a powerful tool designed for comprehensive auditing of large and complex codebases, especially monorepos. It performs cross-stack analysis across C++, Android, iOS, and Web technologies. Key features include classifying files (core code, third-party, build artifacts), identifying known libraries, and assessing code modules into four stages: Core, Extract, Refactor, or Deprecate. Essential for planning major refactoring efforts or inheriting legacy systems.