Mercor system design interview

Round 4 of 5 · 4 questions reported

See the whole loop
Format
Design discussion
Heads-up
Reported prompts include candidate search and LLM evaluation tasks for Mercor's own product.

Questions Mercor asks in this round 4

  • Design ChatGPTSystem designDesign a consumer chat product backed by a large language model: conversations, streamed replies, history across devices, at 100M weekly users.
    Last asked Sep 2026
  • Design a workflow orchestration systemSystem designUsers define a workflow as steps with dependencies, then start runs of it. Design the system that runs each step once its dependencies finish, records the state of every run and…
    Last asked Oct 2026
  • Design a payment systemSystem designAccept card payments for merchants: authorize, capture, settle with card networks, and reconcile, never charging twice or losing money.
    Last asked Oct 2026
  • Design a ticket booking systemSystem designSell seats for concerts and games where demand spikes the moment sales open: hold seats briefly, never sell one twice, and stay up under the rush.
    Last asked Jul 2026