Excalidraw
Hand-drawn style whiteboard for system design and quick diagrams.
Excalidraw's sketchy aesthetic is a feature: diagrams look provisional, so people argue with the architecture instead of the styling. It is the fastest way to draw a system design during an interview or a design review.
Everything runs locally in the browser with optional end-to-end encrypted collaboration, and files export as portable .excalidraw or SVG.
What it's genuinely good at
- Fastest tool for a throwaway architecture diagram
- Free, open source and self-hostable
- Live collaboration with no account required
- Libraries of cloud and infrastructure icons
Where it falls apart
- Not built for polished, presentation-grade diagrams
- Large boards get unwieldy
- Limited layout automation
Alternatives to Excalidraw
Who should use Excalidraw
- System design interview practice
- Architecture discussions and design reviews
- Lecture and study notes with diagrams
What it costs
Free and open source; Excalidraw+ from about $6/month adds hosted workspaces and permissions.
Frequently asked
Can I use it in an interview?
Yes, many remote system design rounds run on Excalidraw and the shared link needs no signup.
Is my data private?
Boards stay in your browser unless you share them; collaboration sessions are end-to-end encrypted.