Startup open‑sources IDE where coding agents draw on a canvas
Whiteboard plugs into Claude Code or Codex and gives the agent an SDK to draw diagrams that link back to the code they describe, its makers say.
Four developers posted Whiteboard to Hacker News on Thursday, an open-source desktop app that gives a coding agent a canvas to draw on. The post had 200 points and 82 comments by early Friday, and the app is free to download.
Whiteboard plugs into agents the developer already runs, among them Claude Code and Codex, and hands them an SDK for drawing on an in-app canvas, according to the repository. Clicking a sequence diagram, an entity relationship diagram or a quote from the agent's trace jumps to the underlying code.
The app is built on CodeOSS, so it carries VS Code keybindings and language server support, the README says. It also ships a semantic diff viewer written in Rust, which summarises large added functions as pseudocode and hides test and documentation changes by default.
The team wrote that agents can query and link their own traces on the canvas, so a reader can see which decisions the agent made on its own. The licence is MIT and the app runs against local checkouts. The makers plan a hosted product for teams, and say it will stay self-hostable.
The post names four founders and lists the project as part of Y Combinator's winter 2026 batch. The README says the app works best with GPT-6 Sol and Claude Opus 5.5. The repository offers downloads for macOS and Fedora, and one commenter asked the team to say so more prominently.