Backend Developer Interview Guide

Backend Interview Guide: APIs, Databases, and Distributed Systems

Backend interviews test API design, database management, distributed systems, and operational excellence. Python, Java, Go, and Node.js are the most commonly tested languages. According to hiring data, backend engineers represent the largest engineering role by headcount at most tech companies.

Backend interviews focus on three layers: data (schema design, queries, scaling), application (API design, business logic, concurrency), and infrastructure (deployment, monitoring, reliability). Strong candidates demonstrate depth in at least one layer and breadth across all three.

Core Backend Topics

• API Design — REST, GraphQL, gRPC. See API best practices
• Databases — SQL/NoSQL, indexing, query optimization. See database design guide
• Distributed Systems — CAP theorem, consensus, replication. See system design fundamentals
• Concurrency — Threading, locks, deadlocks, async I/O
• Testing — Unit, integration, e2e, load testing strategies

Related: full-stack tips, Java questions, Python questions.