API Gateway
An API gateway is a server that acts as the single entry point for all API traffic, routing requests to the correct backend services while enforcing authentication, rate limiting, logging, and…
An API gateway is a server that acts as the single entry point for all API traffic, routing requests to the correct backend services while enforcing authentication, rate limiting, logging, and other policies across all API interactions.
What Is an API Gateway?
An API gateway is a managed entry point that sits between API consumers (clients, applications, partners) and the backend services that fulfill API requests. Every API request passes through the gateway, which applies policies — authentication, rate limiting, routing, transformation — before forwarding the request to the appropriate backend service.
Without an API gateway, clients call backend services directly. With a gateway, clients call the gateway; the gateway handles everything else.
How an API Gateway Works
When a client sends an API request:
1. The request arrives at the API gateway
2. The gateway authenticates the request (validates API key, JWT token, or OAuth credential)
3. The gateway checks rate limits for the requesting client
4. The gateway routes the request to the appropriate backend service based on the request path
5. Optionally: the gateway transforms the request (adds headers, modifies the payload)
6. The backend service processes the request and returns a response
7. The gateway returns the response to the client (optionally transforming it)
8. The gateway logs the request, response, latency, and outcome
From the client's perspective: one URL, one authentication model, one consistent interface. The complexity of the backend is hidden.
Why Enterprise Teams Use API Gateways
Centralized authentication: instead of each backend service implementing authentication independently, the gateway validates credentials once. All backend services trust that authenticated requests from the gateway are legitimate.
Rate limiting and abuse prevention: the gateway enforces limits on how many requests any client can make, protecting backend services from overload. Per-client, per-endpoint, and per-API-key limits are configurable.
Observability: all API traffic flows through the gateway, making it the natural place for logging, metrics, and alerting. Usage analytics, error rates, and latency data are available for all APIs without instrumenting each service individually.
API versioning: the gateway can route requests to different backend versions (v1, v2) based on the request path or headers, enabling API evolution without breaking existing clients.
| API Gateway | Load Balancer | Reverse Proxy | |
|---|---|---|---|
| Primary function | API policy enforcement + routing | Traffic distribution | Request forwarding |
| Authentication | Yes (API keys, OAuth, JWT) | No | No |
| Rate limiting | Yes | No | No |
| Routing logic | Content-based (path, headers) | Availability-based | Path-based |
| Observability | API-level metrics | Connection-level metrics | Request-level logging |
| Best for | Managing API consumers | Scaling backend instances | Routing web traffic |
API Gateway at Dbugger
Dbugger designs and implements API integration layers for enterprise clients — including API gateway configuration for external partner integrations, internal service mesh coordination, and legacy system modernization. We evaluate managed options (AWS API Gateway, Azure API Management) and open-source options (Kong) based on the organization's infrastructure and operational capacity.
Related terms: REST API · Microservices · OAuth · Rate Limiting · Reverse Proxy · Service Mesh
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