I built a free system design whiteboard for engineering interviews

I bombed a system design interview last year — not because I didn't know the architecture, but because I spent the first 5 minutes fighting Excalidraw.

So I built SystemDesignBoard — a free, keyboard-first whiteboard specifically for system design interviews.

What it does

You open it, press a key, and start drawing. No account, no onboarding, no drag-from-a-sidebar friction.

R → place a Service node
C → place a Database/Cache/Queue
A → connect two nodes
N → open the scratchpad for scale math

The features I'm most proud of

Animated connectors that show communication type

Instead of just drawing arrows, connectors visually encode how services talk:

⇄ sync — paired dashes (request + ACK)
≋ stream — near-solid fast line with glow (continuous pipeline)

This matters in interviews — your interviewer can glance at your diagram and immediately understand the communication pattern.

Cloud provider badges

Tag any node as AWS (EC2, Lambda, RDS, S3), GCP (GKE, Cloud Run, Firestore), or Azure. Each subtype has its own icon.

Trade-off logging

Right-click any node → Log Trade-offs → attach your CAP theorem stance, consistency level, and scaling strategy directly to the component.

Diagram-as-Code

Type:
[Mobile App] -> [API Gateway]
[API Gateway] -> [Auth Service]
[Auth Service] -> [Users DB]
[Feed Service] -> [Posts DB x3]
[Feed Service] -> [Redis Cache]
Hit Apply — it auto-lays out the whole architecture in seconds.