System Design Sandbox is the interactive playground for system design interviews. Drag and drop real components (load balancers, caches, Kafka, shards, etc.), build your architecture, and get instant AI feedback that catches missing rate limiters, single points of failure, wrong consistency choices, and more with clear fixes. TinyURL scenario is live and 100% free, no signup. More scenarios drop every week. Stop drawing boxes on Excalidraw. Start practicing the way you think.

AppSignal — Real-time monitoring that helps you ship with confidence

Real-time monitoring that helps you ship with confidence

What inspired you to build this? What problem were you trying to solve? How did your approach or process evolve while working on this launch? I built System Design Sandbox after bombing my own system design interview at a Big Tech company. Drawing boxes on a whiteboard felt clunky – no quick feedback, endless second-guessing on trade-offs like caching vs. sharding. Existing tools were either too rigid (pre-built templates) or too vague (no AI smarts). I started with a simple drag-drop canvas, but iterated to AI scoring after testing with 20+ engineer friends – they loved catching "oops" moments like missing consistency models. Now it's live with TinyURL, evolving weekly based on user replies. If you're grinding LeetCode + systems, what's your biggest pain? Try it and lmk!

AppSignal — Real-time monitoring that helps you ship with confidence

Real-time monitoring that helps you ship with confidence

System Design Sandbox

Interactive system design practice with AI feedback

Interactive system design practice with AI feedback