API Gateway

API gateways centralize management of API traffic, reducing complexity for backend services and providing consistent security and observability.

Why it matters

• Eliminates duplicate authentication and authorization logic across services.
• Provides a single point for rate limiting, preventing abuse and ensuring fair usage.
• Enables traffic management, including load balancing and A/B testing.
• Simplifies client integration by aggregating multiple backend services.
• Essential for microservices architectures where dozens of services need unified access control.

Key capabilities

• Request routing: Direct traffic to appropriate backend services based on path, headers, or content.
• Authentication: Validate API keys, OAuth tokens, JWTs, or mutual TLS certificates.
• Rate limiting: Protect backends from traffic spikes and enforce usage quotas.
• Request transformation: Modify headers, query parameters, or body content.
• Response caching: Reduce backend load for frequently requested data.
• Logging and analytics: Centralized visibility into API usage and performance.

Common patterns

• Edge gateway: Single entry point for external API traffic at the network perimeter.
• Internal gateway: Manages service-to-service communication within a cluster.
• Backend for Frontend (BFF): Specialized gateways optimized for specific client types (mobile, web, IoT).

Security best practices

• Terminate TLS at the gateway and use mutual TLS for backend connections.
• Implement OAuth 2.0 or OpenID Connect for token-based authentication.
• Apply rate limiting and throttling to prevent denial-of-service attacks.
• Validate and sanitize all incoming requests to prevent injection attacks.
• Log all requests for security auditing and incident investigation.

Popular implementations

• Cloud-native: AWS API Gateway, Azure API Management, Google Cloud API Gateway.
• Open source: Kong, Tyk, KrakenD.
• Service mesh: Istio Ingress Gateway, Envoy.