Architecture Overview

Excalidraw is a Yarn-workspaces monorepo: the whiteboard itself lives in packages/excalidraw (a React component library published to npm), with element geometry/rendering logic split into packages/element, shared primitives in packages/common and packages/math, and the excalidraw.com product built on top in excalidraw-app/. A new hire's mental model should be: App.tsx (the giant React component) owns UI state and pointer/keyboard events, Scene + Store hold the element data and undo history, and the renderer/ modules paint that data onto layered HTML canvases.