What is an API?

API stands for application programming interface. 

A backbone of modern digital experiences and interconnected devices, APIs help facilitate seamless communication between software systems and applications, helping them exchange data and access functionality.

How are APIs used?

APIs are used in myriad ways in applications we all use every day.  It would be impossible to do online banking, use a mobile app, or, in some cases, even start our cars without APIs. Anywhere two systems need to communicate, APIs are usually the way to do it.

For example, online stores use APIs to link with ecommerce payment systems, letting customers make safe payments without leaving sites. APIs bring real-time conditions from weather providers to mobile devices. Websites often use APIs to suggest related (“you may also enjoy”) content recommendations for readers browsing articles and pages.  

Increasingly, APIs are central to the way we interact with the physical as well as virtual world. Connected Internet of Things (IoT) devices collect vast amounts of data, which can be processed, analyzed, and used in a multitude of ways. APIs provide the means for IoT devices to communicate this data to other systems, facilitating actions like remote monitoring and control.

A brief history and common types of APIs

APIs aren’t new. In fact, they’ve gone through decades of evolution. Remote Procedure Calls (RPC) date back to the 1970s and are still in use today. 

By the 2000s, the popularity of RPC waned in favor of Simple Object Access Protocol (SOAP). SOAP, in turn, was largely supplanted by Representational State Transfer (REST), which, unlike SOAP, was stateless and tended to be less “chatty,” enabling more modern and higher-scale applications.

Today, among the most prevalent types of APIs are REST APIs and GraphQL. Below, we explain the functionality of each and their key differences.


REST APIs adhere to the REST architectural style. They use a resource-based approach where each resource is identified by a unique URL. 

REST APIs use HTTP, the same protocol that powers websites to communicate with and access server data. Clients can use standard methods like GET, PUT and DELETE to access and manipulate data on the backend.

Their widespread adoption stems from their simplicity, flexibility, and support across various programming languages and platforms. However, REST APIs can be verbose and require multiple requests to fetch related data.


GraphQL, an alternative to REST APIs, empowers developers with greater flexibility and control over data fetching. Unlike REST APIs, which provide predefined data structures, GraphQL allows clients to specify the exact data they require through a query language. 

This approach optimizes data transfer, reducing unnecessary network traffic and enhancing performance. GraphQL’s adaptability makes it particularly suitable for complex data retrieval scenarios and applications with intricate data relationships.

APIs, CMSes, and composable frontends

One way APIs are increasingly being used is to build more differentiated digital experiences that pull data and content from a multitude of different systems at the front end. 

Commonly called “composable” systems, they use APIs to access backend services such as content management systems (CMS), ecommerce systems, marketing automation platforms, digital asset management (DAM), product information management (PIM), customer data platforms (CDPs), customer service systems, and other applications. 

No two composable experiences are the same, which is why APIs are so important. They act as the conduit to backend information, enabling each business to build the right experience for their unique needs.

Furthermore, APIs are also crucial to enabling omnichannel experiences. By leveraging APIs, businesses can easily deliver content and functionality through emerging channels, such as mobile apps, IoT devices, and custom user interfaces.

Managing API sprawl with API mesh

Managing APIs that power composable experiences can become a challenge. 

While using one API can be simple and straightforward, integrating and managing a whole series makes development work increasingly taxing for engineers, who must ensure optimal performance for each one.

This requires middleware to manage connectivity to all APIs, ensure performance, handle retry logic, transform and assemble data, enable caching and indexing, and much else. 

For developers, API mesh architecture simplifies the complexity of managing multiple APIs by abstracting the underlying services and presenting them as a single cohesive interface.

APIs and WordPress VIP

WordPress VIP is a popular CMS for use with API-driven architectures. It provides a multitude of APIs. For example:

Overall, this architectural approach enhances flexibility and scalability for developers, allowing businesses to reach a wider audience and provide seamless experiences across multiple platforms.