Why REST API Design Matters More in Microservices
In a monolith, a poorly designed internal API is an inconvenience. In a microservices architecture, it becomes a cascading liability. Every service-to-service call is a network boundary with latency, failure modes, and versioning implications.
Enterprise teams operating 20+ microservices often discover that their biggest bottleneck is not compute or storage but API contract misalignment. The investment in deliberate REST API design pays compound returns.
Start with Domain-Driven Resource Modeling
The most common mistake is modeling resources around database tables instead of business domains. An /orders endpoint should represent the business concept of an order, not the orders table in your PostgreSQL instance.
API Versioning Strategy That Survives Production
Every enterprise team that skipped versioning regretted it within 6 months. The question is not whether to version, but which strategy minimizes coordination overhead.
Authentication and Authorization Across Service Boundaries
Security in microservices is not a single checkpoint — it is a layered strategy that balances external access control with internal service trust.
- Use an API gateway as the single entry point for external traffic with OAuth 2.0 token validation.
- Issue JWT tokens with scoped claims: user identity, roles, and tenant ID so downstream services can authorize without additional lookups.
- For service-to-service calls, use mutual TLS (mTLS) or machine-to-machine OAuth tokens. Never pass user credentials between services.
- Implement least privilege at the API level — each service only exposes what its consumers actually need.
- Centralize identity management but distribute authorization decisions to each service domain.
Error Handling and Resilience Patterns
In a distributed system, failures are expected operating conditions, not exceptions. Your API design must account for partial failures, timeouts, and degraded states.
Rate Limiting and API Governance
Pagination, Filtering, and Query Design
Enterprise data volumes make efficient query design non-negotiable. A /transactions endpoint without pagination will eventually bring down your service.
- Use cursor-based pagination for large datasets. Offset-based pagination degrades at scale.
- Return pagination metadata: next cursor, total count (when cheap), and hasMore boolean.
- Support field filtering with ?fields=id,name,status to reduce payload size.
- Implement consistent sorting with ?sort=-createdAt,name for multi-field ordering.
- Use structured filter syntax (?filter[status]=active&filter[amount][gte]=1000) for complex queries.