Buildermark is a powerful, open-source tool designed to track and analyze the extent to which coding agents contribute to software development projects. It matches agent-generated edits against git commit diffs, offering insights into the proportion of automatically generated versus manually written code. The tool supports multiple AI coding assistants like Claude Code, Codex, Gemini, and Cursor, making it versatile for different workflows. Buildermark is local-first with no analytics or tracking, ensuring privacy and control over your data. It can be run locally by opening a frontend at localhost:55022 after importing the project details. A browser extension is also available to streamline imports from cloud-based coding agents.