Whiteboard

Whiteboard is an open-source desktop app where humans and coding agents can architect software together on a shared canvas. It plugs into tools like Claude Code and Codex, giving agents an SDK to draw sequence diagrams, entity models and decision traces directly on the board.

The app includes a semantic, AST-aware diff viewer written in Rust that filters noise from code changes — large added functions get summarized as pseudocode, and test or doc changes collapse by default. A WASM plugin system lets you customize what gets shown.

Whiteboard also tracks the decisions agents make autonomously, linking their traces to requirements on the canvas so you can see what was specified, what was implemented, and where the agent improvised. MIT-licensed, runs against local checkouts, and works best with GPT-6 Sol or Claude Opus 5.5.