Plannotator is a React-based annotation tool that intercepts Claude Code's ExitPlanMode to provide visual plan review with collaborative features. It opens a UI in your browser when Claude Code calls ExitPlanMode, allowing you to mark up and refine plans visually.

The tool offers markdown plan rendering with syntax highlighting and text selection annotations including delete, replace, insert, and comment functionality. It includes redline mode for quick deletion marking, URL-based sharing via compressed hash without server storage, and a tater identity system for anonymous collaboration. Additional features include export to diff format, dark/light theme support, and tater sprite easter egg.

When Claude Code calls ExitPlanMode, the hook intercepts and opens the Plannotator UI in your browser. You can then annotate the plan visually and either approve to let Claude proceed with implementation or request changes which sends your annotations back to Claude.

The benefits include visual plan review capabilities, team collaboration features, and seamless integration with Claude Code's workflow. It runs entirely locally in your browser with no network requests, ensuring plans never leave your machine.

Plannotator is designed for developers using Claude Code who need to review and collaborate on AI-generated code plans. It integrates automatically with Claude Code plan mode and supports anonymous collaboration through its tater identity system.