What Is an API Gateway?

An API Gateway is a server that acts as a single entry point for all client requests to your backend services. Instead of clients communicating directly with each service, they send their requests to the API Gateway, which then forwards the requests to the appropriate service.

The main purpose of an API Gateway is to simplify how clients interact with your system. By handling all incoming requests in one place, you can manage security, routing, and other important features more easily and consistently. This approach also allows you to hide the details of your backend services from clients, making your system more secure and easier to maintain.

Key benefits of using an API Gateway:

• Centralizes and manages all incoming API requests;
• Simplifies client interactions by providing a single access point;
• Improves security by handling authentication and authorization in one place;
• Enables features like rate limiting, logging, and monitoring for all services;
• Makes it easier to update or change backend services without affecting clients.

You will use an API Gateway to build secure, scalable, and maintainable systems, especially as your application grows and includes more services.

How an API Gateway Sits Between Clients and Backend Services

An API Gateway acts as a middle layer between your clients (such as web browsers, mobile apps, or other services) and your backend services (like user management, order processing, or payment systems). When a client sends a request, it does not talk directly to the backend service. Instead, the request first goes to the API Gateway.

How Requests are Routed

• The API Gateway receives each client request;
• It checks which backend service should handle the request;
• It forwards the request to the correct backend service;
• It collects the response from the backend service and sends it back to the client.

For example, if a mobile app requests user information, the API Gateway sees that this request should go to the user service. If another request is for making a payment, the API Gateway routes it to the payment service.

Basic Security Features

The API Gateway helps protect your backend services by providing basic security features:

• It can check if a client is authorized to access a specific service;
• It can block suspicious or unwanted requests;
• It can hide the internal details of your backend services from clients.

Suppose a client tries to access order information without being logged in. The API Gateway can reject this request before it ever reaches the order service, keeping your backend services safer.

By acting as a gatekeeper, the API Gateway simplifies communication between clients and backend services and adds an extra layer of security.