What is an API Gateway and How Does it Work?


An API gateway is responsible for taking all API requests coming from clients and making sure that they are routed to the right microservice with composition, request routing, and protocol translation. This means that when a request is sent, it invokes different microservices and aggregates the results to ensure that the request gets the correct path. 

An API might send or receive multiple requests. This even gets more when there are many APIs involved. The whole process of sending requests and receiving responses would be very complicated if it was not for the API gateway. It manages all the requests and the responses making sure that each one of them has the right resources, uses the right path, and ends up at the right destination.

For example, a mobile user who wants to get all the details about a product on an e-Commerce website gets an endpoint from the API gateway. This endpoint gets all the details about any product that the user wants within a single request. This is how the API gateway makes the whole process easy.


Why Should Developers Use an API Gateway?

As discussed above in the definition of an API gateway, the gateway makes the entire process of sending and receiving requests easy. As an API developer, one needs to make sure that their clients are happy with the services they are getting, and they are not involved in the entire workflow of the API.

However, the API developer has a number of concerns that they do not want to interfere with the experience of the API users. For instance;

  • They have added monitoring and analytics tools to get different usage metrics on their APIs.
  • They use rate-limiting, authorization, and authentication services to avoid abuse and overuse of their APIs.
  • They have connected their APIs to a billing system – for those with monetized APIs.
  • They might add new services while retiring others over a period of time, but want to make sure that their clients get all the services at a central place all the time.


These are just some of the concerns, but API developers need to provide their clients with a dependable and seamless experience even through the above complexities. This is where the role of the API gateway comes to play. It decouples the backend of an API’s implementation from the interface used by the clients. 

In a nutshell, when a request from a client is made, the gateway gets the request, breaks it into various requests, and makes sure that they are routed to the right destinations. When a response is made, the gateway gets the response and ensures that it goes to the right places.


How an API Gateway Works

Supporting Serverless and DevOps Environments

Today, cloud development, as well as serverless environments, rely on APIs to provision their infrastructures. However, management of such environments had not initially been easy without the API gateway. Serverless functions are now being deployed and managed by the API gateway, making the whole process easy and straightforward. 

In addition, some companies deploy the DevOps approach in the development of their software applications. They iteratively build and deploy applications using microservices since they (microservices) are able to communicate and share data through the use of APIs. When requests and responses are involved, an API gateway is required to help manage them.

Due to advancements in technology and the growing importance of big data in modern businesses, we are seen more interconnectivity and integration between applications, driven by APIs. This increases the complexity of APIs, making the API gateway very important.


API Management

An API management platform depends on an API gateway when performing a number of functions. As discussed, it gets all the requests and passes them through the management platform which initiates a number of other important functions. 

The gateway is responsible for several things that are considered a responsibility of the API management platform. This might include rate-limiting, routing, authentication, authorization, analytics, monitoring, and billing among others. 


Building Microservices

When building microservices, developers have realized that they need an API gateway to work as the only entry to the entire application. This is because the gateway is tasked with protocol translation, composition, and routing, making sure that the system works seamlessly and meets its obligations.

The API gateway makes sure that the clients accessing the system get their own customized API. Through this, their requests are routed to the right services in the backend. The gateway also responds to some of the requests by making sure that the right backed services are invoked and results aggregated without any issues. 

In situations where the system is facing any issues in the backend, the API gateway makes sure that the issues are masked, then returns default or cached data. This way, developers are now able to build microservice-based applications with the help of the API gateway, making sure that the systems work well with simplified processes.



An API gateway sits between the client and the API’s backend services. It makes sure that API users are not bothered with all the backend work that makes sure that the API works well and meets all its responsibilities. This allows the users to just use the API the way they want, avoiding any complexities that might derail their work. The gateway is, therefore, a very important component that determines how successful an API will be.