Case study · Productivity · 2025
Excalidraw+ · an extended Excalidraw with unlimited diagram size and presentations built in
Excalidraw is the best tool for sketching architecture — until the board gets big and the browser starts to struggle. Excalidraw+ removes that ceiling and adds the one feature every engineer wanted: presenting the board as slides.
The problem#
Large system diagrams — a whole platform with its services, queues and data stores — are exactly where a whiteboard is most useful and where Excalidraw slowed down. And when the diagram was done, presenting it meant exporting screenshots into another tool.
What I built#
- No practical limit on board size: canvas virtualisation so that big architecture maps stay smooth to pan, zoom and edit.
- Presentation mode: step through frames of a board as slides, straight from the whiteboard.
- Everything else Excalidraw does, kept intact: the hand-drawn style, collaboration, exports and shortcuts.
How#
A fork of Excalidraw (TypeScript, React) with the rendering path reworked to virtualise what's off-screen, plus a presentation layer over the existing frames feature. Careful engineering rather than a rewrite: the goal was to stay upgradeable against upstream.
Outcome#
A live tool I use for my own client architecture sessions — the diagrams in my system-design work start here — and an example of the kind of focused, practical extension of open-source tools that teams often need.
More work
