What is an API Gateway? The Front Door for Your APIs
An API gateway is a managed service that sits between clients and backend services, handling authentication, routing, rate limiting, and observability for all API traffic. Learn how API gateways work and why they are essential in microservices and enterprise architectures.
What is API Gateway?
An API gateway is a server that acts as the single entry point for all API requests to a system. It receives incoming calls from clients, applies cross-cutting policies — authentication, authorization, rate limiting, request transformation, and logging — then routes the request to the appropriate backend service. Rather than each microservice implementing these concerns individually, the gateway centralizes them.
- Single entry point for all external API traffic
- Handles auth, rate limiting, routing, and request/response transformation
- Decouples clients from internal service topology
- Provides centralized observability: logging, tracing, metrics
- Examples: AWS API Gateway, Kong, Apigee, Azure API Management
How API Gateway Works
All client requests hit the gateway first. The gateway authenticates the caller (API key, JWT, OAuth token), enforces rate limits, optionally transforms the request, and routes it to the correct backend service. The backend responds; the gateway may transform the response before returning it to the client.
Request received
The client sends an API request to the gateway URL. The gateway handles TLS termination, so backends receive plain HTTP internally.
Auth and policy enforcement
The gateway validates the caller's credentials (API key, OAuth Bearer token, JWT), checks scopes and permissions, and applies rate limits.
Routing and transformation
The gateway maps the incoming path to the correct backend service, optionally transforming the request (headers, body, protocol) before forwarding.
Response and observability
The backend responds; the gateway logs the request, emits metrics, and returns the response to the client — with optional response caching or transformation.
Common API Gateway Use Cases
Microservices facade
Expose dozens of internal microservices as a single, versioned public API surface — clients see one domain, not an internal service mesh.
Third-party API monetization
Apply per-customer rate limits and usage quotas, generate API keys, and track consumption for billing via the gateway.
Enterprise integration hub
Route AI agent requests from FlowGenX workflows to the correct internal or external service, applying auth and rate-limit policies centrally.
API Gateway in FlowGenX AI
FlowGenX integrates with API gateways — AWS API Gateway, Kong, Azure APIM — as both a consumer and a trigger source. Workflow steps can call any API behind a gateway with proper auth credentials managed by Integration Studio. You can also expose FlowGenX webhook endpoints behind your own gateway for enterprise-grade traffic control and audit.
Frequently Asked Questions
See It In FlowGenX