What is an API Gateway?

This content was last reviewed on: 
November 24, 2022

A Quick Intro to the API Gateway

The API gateway is an important part of any application, acting as a point of passage for data within your application to reach the desired endpoints. It is often used by backend systems for routers, load balancers, or databases. Today, we’ll discuss the API gateway, what it does, some useful features, and why modern developers rely on them.

As the world becomes increasingly interconnected, the API gateway has grown in importance in the tech industry. Probably the most obvious reason for its growing significance is that its use provides a way for companies to integrate various technologies and systems, making it easier to manage and use information from APIs.

The Application Programming Interface gateway, usually referred to as the API gateway, is a software that enables communication between multiple applications and systems being used. It creates an interface between external applications and internal systems. The API gateway assists in managing and securing any APIs in use by providing authentication and authorization features.

In this post, we'll cover the following topics:

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Why is the API Gateway Important?

In brief, API gateways:

  • Simplify the process of building APIs
  • Improve the reliability and usability of your applications
  • Can automate certain tasks, such as authentication and authorization

The API gateway is an invaluable tool for web and mobile app developers. It enables them to create APIs that allow third-party developers to access and use the functionality of their applications. This can save developers time and money, as well as improve the reliability and usability of their applications. Additionally, API gateways can help to streamline the development process by automating certain tasks, such as authentication and authorization.

Using an API gateway can significantly improve the performance of applications by allowing them to interact with external systems in a faster, more efficient way. An API gateway manages the interaction between an API provider and API consumer. It manages all the requests made to the different APIs and aggregates the result. They protect user information, securing and mediating all traffic between backend apps that may expose data.

The infographic is enclosed in a yellow rectangle. The top center is labeled “API Gateway Setup Example.” Below there are three areas, the left, middle and right. On the left, in descending order we see the terms, “Mobile App,” “Developer,” and “Web App.” Each has an arrow from the label pointing toward the center toward a yellow rectangle labeled API Gateway. Then, from the API Gateway in the center, we see arrows pointing to the left. They point to each of three terms, “Microservices,” “Database,” and “Business Apps.” 
API Gateway Workflow

API gateways help with functionalities like API call routing, throttling, rate limiting, policy enablement, security mechanism, and other tasks. And in addition to authentication and authorization, API gateways automate complex processes, such as customer interactions or supply chain management.

Previous Uses for API Gateways

The increase in the use of API gateways has made it easier for developers to avoid using monolithic applications, which relied on services built with an all-in-one architecture linked by a single database. The problem with these applications is that all components are dependent on each other because they work together to create a singular unit.

That’s great until changes need to be made. With monolithic applications, any modifications to part of an application may mean changing the entire architecture, a developer’s nightmare.

As the Internet grew from Web 1.0 technology to the innovations of Web 2.0, developers soon realized that API gateways need to be more than “glorified routers.” Without this change, monolithic APIs and architectures would continue to be the norm. So, the move toward more cloud-based systems has made the need for API gateways more critical than ever.

What are the Benefits of Using an API Gateway?

Because modern API gateways work with multiple APIs across systems, their use offers several services and efficiencies essential to workflow.

One example of their usefulness: API gateways are easy to configure, providing more flexibility to development teams. They can also extend the functionality of some legacy applications, and be used for monitoring and observation. Logs can help determine where issues starting during failure events.

Some other benefits of using API Gateways include:

  • They add additional layers of security. Using an API gateway protects your APIs by enforcing security rules and restricting access to authorized users only. This reduces the chances of malicious attacks targeting your API resources.
  • Performance may be optimized by API gateways. That’s because API gateway takes advantage of modern cloud technologies to provide optimized performance for your APIs. This means your users will experience quicker responses times and lower consumption of resources. 
  • API gateways maximize reuse and adoption by discovery through API developer Portals.
  • API gateways can also provide metrics for API Consumption as well as monitor SLAs for Traffic Management.

Some Basic Features to Look for in an API Gateway

Every project is different, but any API gateway search should include the following criteria:

  • Authentication and Authorization
  • Traffic Observability
  • Traffic Management
  • Security

Other Questions to Ask Before Choosing an API gateway

Meanwhile, here’s a quick set of questions you may want to consider when evaluating API gateways.

  1. First, do you want proprietary or open source?
  2. What about architecture? Are you looking for something simple and easy to use, or do you need extensibility for scale?
  3. Does the system you’re considering meet your needs, and integrate with APIs already being used?
  4. What about customization, and programming languages used?

What about API Proxies?

API proxies are a subset or miniature version of an API gateway. For some they may do enough to get the job done for a project, but in general API proxies are limited in what they provide. They may offer some basic communication between platforms, control traffic flow, and some security and monitoring features for users, but won’t allow you to do much else. API gateways will provide better routing, content, analysis and monitoring, and much more.

Open Source/Free API Gateway Tools

Here are some of the best open-source API gateway tools available today.

  • Kong is one of the most popular open-source API gateways. It is highly scalable and offers a rich feature set, including plug-ins for security, monitoring, and logging. For what it’s worth: Kong is written in Lua and runs on top of NGINX.
  • Tyk is another popular open-source API gateway. It is written in Go and provides a self-service portal for developers to manage their own APIs. Tyk also offers a commercial version with additional features such as analytics and support.
  • Zuul, which comes from Netflix’s open source initiative, is a JVM-based router and server-side load balancer. It provides dynamic routing, monitoring, resiliency, and security features.
  • Apache Camel is an integration framework that includes an API gateway component. Camel's API gateway allows you to define policies for your APIs, such as rate limiting or authentication. Apache Camel is written in Java.
  • Gravitee.io is an open-source API management solution for Java. It is a lightweight library that helps you create and manage the APIs you need to connect your applications to your data sources. Gravitee.io features include API design, documentation, versioning, and testing.
  • AWS API Gateway is an HTTP-based RESTful API gateway service from Amazon Web Services (AWS). It can be deployed in any public or private cloud, including AWS and on-premises data centers. Amazon API Gateway's primary functions include routing requests, enforcing policies, discovering and monitoring APIs, applying transformations and access control mechanisms.
  • IBM UrbanCode Deploy is a RESTful API gateway that allows users to define rules to handle incoming requests based on URL patterns and other factors.

How is API Gateway Evolving? 

As mentioned earlier, the API gateway has evolved, transitioning over the years from being used in Web 1.0/monolithic architectures to becoming an essential part of any modern microservices-based architecture. The API gateway provides a single point of entry for all your API calls and can be used to route traffic to the appropriate backend service. 

With the development of microservices architecture and cloud-native applications, more features were built into the API gateway itself. 

Let’s look at what this means for development teams:

  • First, there’s API routing, which is the ability to route traffic from different origins to different endpoints. 
  • The most important part of the architecture is that the API gateway is a point of contact between the UI layer and the business logic layer.
  • The business logic layer consists of all the microservices, including data providers, data managers and data publishers.
  • Because an API gateway sits on top of the application (i.e., the boundaries of the system or application) and provides an entry point for all the API consumers, having a unified way to configure and manage it is important. This includes integrating different authentication mechanisms (OAuth 2, OpenID Connect), authorization tokens, rate limiting policies and throttling rules for different APIs. Also included in this list are security (SSL/TLS), logging, analytics, and metrics.

Limitations of API Gateways

Every great innovation comes with its share of drawbacks. Like any other web-based application, API gateways can be slow and unreliable or scale poorly.

Other issues you may have to deal with from time to time with your API gateway

  • The extra step of having a request pass through API gateways may lead to slower response times in some applications.
  • Some system dependencies may also cause problems as you scale up. Any additions, removals, or adjustments to existing systems may be difficult, depending on the architecture used. However, careful API design rules can reduce or eliminate this problem.
  • Routing logic may make communication more complex when dealing with microservices.
  • If the only API gateway in use experiences an outage, then that impacts your entire application. Developers can use multiple API gateways and load balancers to mitigate this risk. 

Conclusion

To recap, the API gateway is an essential and cost-effective solution to make your developers more productive by offloading the work of managing APIs while providing better performance, and safety controls.

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