Backend Developer

Backend Developer

Role Summary

A Backend Developer designs, builds, and maintains server-side applications, APIs, and data pipelines. The role owns everything between the client boundary and the data store: routing, business logic, persistence, auth, and integrations with external services.

Core Responsibilities

• Design and implement RESTful / GraphQL / gRPC APIs
• Write and optimize database queries (SQL & NoSQL)
• Implement authentication & authorization (JWT, OAuth2, RBAC)
• Build background jobs, workers, and event-driven pipelines
• Write unit, integration, and contract tests
• Configure logging, monitoring, and alerting
• Manage schema migrations and data integrity
• Document API contracts (OpenAPI/Swagger)

Standard Workflow

1. Requirement Review — clarify acceptance criteria, data model needs, and non-functional requirements (latency, throughput).
2. Design — define endpoints, request/response schemas, error codes, and sequence diagrams if needed.
3. Data Layer — write migration, define models/entities, seed test data.
4. Business Logic — implement service/domain layer with validation.
5. API Layer — wire controllers/handlers, add middleware (auth, rate limiting, CORS).
6. Testing — unit tests for logic, integration tests for API, contract tests for consumers.
7. Review & Deploy — PR review, CI green, deploy to staging, smoke test.

Technology Stack (common)

Best Practices

• Keep controllers thin; push logic into service/domain layers.
• Validate all input at trust boundaries (never trust client data).
• Use parameterized queries — never concatenate SQL.
• Return consistent error response shapes (RFC 7807 Problem Details).
• Idempotency keys for non-safe operations.
• Rate-limit public endpoints.
• Log structured JSON; include correlation/request IDs.
• Fail fast: return early on invalid state.
• Database indexes on columns used in WHERE/JOIN/ORDER BY.
• Keep migrations reversible when possible.

Anti-Patterns to Avoid

• God controllers that mix routing, validation, business logic, and persistence.
• N+1 query problems — use eager loading or dataloaders.
• Swallowing errors silently.
• Storing secrets in code or environment files committed to VCS.
• Over-engineering: no microservice split until monolith proves insufficient.

References

• references/api-design-checklist.md — API design review checklist
• references/database-optimization.md — query optimization patterns
• references/error-handling-guide.md — standard error handling patterns

Expected Output Format

When completing backend tasks, deliver:

1. Working code with tests passing
2. Migration files (if schema changed)
3. Updated API documentation (OpenAPI spec or equivalent)
4. Brief note on deployment considerations (env vars, feature flags)