This repository contains a tool named `xcdiff` for comparing two Xcode project files (.xcodeproj) and outputting their differences in multiple formats. It is designed as both a command-line utility and a reusable Swift library (XCDiffCore). The tool analyzes structural and configuration differences between projects, including targets, sources, headers, resources, build settings, and dependencies. The architecture follows a modular, plugin-like design where each aspect of the project comparison is handled by a separate comparator implementing a common protocol. This allows for easy extension with new comparison types. Results are rendered through a similarly abstracted renderer system, supporting output formats such as plain text, JSON, markdown, and HTML. The tool is actively maintained and keeps pace with evolving Xcode project formats, as evidenced by fixtures for recent Xcode features like synchronized groups.