Engineering · 2026 Guide
Backend Engineer Interview Questions
Backend Engineer interviews focus on API design, databases, distributed systems, and scaling. Expect coding rounds plus 1–2 system design rounds covering high-throughput services.
Core Interview Topics
Backend Engineer interviews at top tech companies typically assess these competency areas:
Top 10 Backend Engineer Interview Questions
These questions are drawn from real interview loops at FAANG and top-tier tech companies in 2025–2026. Click Practice now to run a full AI mock session for any question.
- 1
Design a rate limiter that supports per-user and per-endpoint limits.
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How would you migrate a monolith to microservices? What are the pitfalls?
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Explain CAP theorem with a real-world tradeoff you have made.
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Write SQL to find the second-highest salary per department.
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When would you use Kafka vs RabbitMQ vs SQS?
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How do you handle idempotency in a payment API?
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Design a notification service that delivers 1B messages per day.
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Walk through index selection in PostgreSQL — B-tree vs hash vs GIN.
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How do you debug a thundering herd cache stampede?
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Explain eventual consistency with an order-fulfillment example.
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How to Prepare
- ✓Master one SQL dialect deeply (window functions, CTEs, EXPLAIN).
- ✓Read "Designing Data-Intensive Applications" — at least chapters 1–9.
- ✓Be able to draw a sharded, replicated DB with read/write paths from memory.
- ✓Practice API design: resource naming, versioning, pagination, errors.
ATS Resume Keywords
Include these high-signal keywords in your Backend Engineer resume to pass ATS filters at top companies.
Resume must-haves for Backend Engineer:
- Throughput / latency numbers
- Specific DBs and queue tech
- On-call experience
- Migrations or scale events