Sumicat, an infinite whiteboard drawn with a real sumi brush

Sumicat is a whiteboard whose brush is a fourteen-hair simulation with a two-tank ink reservoir, drawing on paper with a tooth. Boxes, ellipses, diamonds, arrows and text work as they do on any whiteboard, except that a shape's edge is drawn by the brush rather than stroked as a vector, so corners carry the same ink dynamics a hand-drawn corner does.

A board is saved in your own browser until you share it. Sharing makes a private board with separate edit and view links, live cursors, a laser pointer and shared undo. Everything on it can be exported as a PNG or as an editable board file.

An AI agent can draw here too. The Model Context Protocol endpoint at /mcp lets an agent create a board, draw brush strokes from SVG path data, add shapes and text, read what is already there and undo its own work. The full guide for agents is at /llms.txt.

Made by alcun.dev.