tandem

A multiplayer infinite canvas where you and your AI agent make things together—it searches, places, and arranges beside you, live on the same surface, with every move visible.

- describe what you imagine, alone in a chat
+ make it together on one shared canvas
Bring your agentWebMCP

Open any board in ChatGPT’s in-app browser—or Chrome 149+ with the WebMCP flag—and your agent discovers eight canvas tools. They call the same multiplayer mutations your cursor does.

document.modelContext.registerTool({ name: "canvas_add_note", … })

No account. Boards live at their URL:

read the source—github.com/lnittman/tandem

Open source under MIT. Built in the open for the WebMCP Challenge, Aug 29–Sep 3, 2026.