OpenAI Backend Engineer Interview Questions

800+ verified questions, indexed by team and level. Real questions submitted by candidates who completed OpenAI loops in the last 24 months.

About the OpenAI Backend Engineer hiring loop

OpenAI rounds are heavy on ML system design (training infra, inference at scale, RLHF pipelines) and deep technical depth in your specialty. Behavioural rounds probe research-product collaboration. Bar is unusually high; rejection rate ~98%.

Backend rounds score on API design quality, database-tier reasoning, scalability anchoring, and operational maturity (observability + reliability). Trade-off articulation differentiates Senior from Mid.

Topics covered in OpenAI Backend Engineer interviews

  • 01API design (REST, GraphQL, gRPC, idempotency, versioning, pagination)
  • 02Database design (relational vs document vs wide-column, indexing, query plans)
  • 03Caching strategies (read-through, write-through, write-back, invalidation)
  • 04Concurrency + async (threads, event loops, queues, distributed locks)
  • 05Authentication + authorization (OAuth, JWT, RBAC, ABAC, session management)
  • 06Observability (logs, metrics, traces, SLOs, error budgets)

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