ViewVC is an open-source web-based application that provides a user-friendly interface for browsing source code repositories managed by version control systems such as Subversion and CVS. It allows users to navigate directories, view files, and track changes in the repositories, making it an essential tool for developers and project managers who need to oversee and audit codebases efficiently. The software offers functionalities like diff viewing, annotation, and log access, enhancing collaboration and code management.