System Design AI

Guided practice

Start with a template. Work through each step. Ask Coach when you need a second opinion.

Classic designs 1

Ordered by design number

Company tags are community-reported. Counts on cards show how many people reported that design.

SandboxingClear filters

47. Design an Online Judge like LeetCode
Run strangers' code safely in single-use microVMs, return verdicts within 5 seconds, and rank 100,000 contestants live.
ClassicMedium
Caching Queues Databases
+8
Security AWS Firecracker Leaderboards Online judge Redis Sandboxing Amazon SQS
Worked design
Practice

Self-paced by default. Your answers and canvas stay private. AI feedback runs only when you ask for it.