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Design an Online Coding Judge is a medium system design interview question covering Distributed Systems, security, queues, sandboxing — the kind asked at FAANG (Facebook/Meta, Apple, Amazon, Netflix, Google) and AI-first companies like Anthropic, OpenAI, and Nvidia.
Design a platform like LeetCode's judge: users submit source code in 10 languages, the system compiles it, runs it against hidden test cases, and returns a verdict. Steady state is 500 submissions/sec, but a rated contest opens with a 20,000/sec spike. The code is completely untrusted, verdicts must be identical across machines, and hidden test cases must never leak.
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