The Most Detailed API Classification

When it comes to APIs, it is not enough to just get the definition of it. In order to truly understand what an API is, you should also discover many types of APIs. They are emerging over time, bringing up numerous benefits. The first API was designed in different circumstances that the APIs today. That is why their language and architecture are different. However, APIs landscape always provided a good API perspective.

As we mentioned above, APIs are enabling many benefits and implications. When it comes to designing an API, its style is probably the most important factor that defines the usability of API. API style influences the overall impression and affects API’s consummation. When a developer is designing an API, he should have in mind that he has to create a consuming API, that will say much for itself once it is released. Besides that, a developer has to take into account possible constraints that might step in the way during the process.

Basic API Models

The most general and most known API classification divides APIs as Public and Private ones. They are defined by the way of their adoption and how they are shared through the system. Private APIs are also known as internal APIs. They are meant for the internal use, just like their name says. Companies use internal APIs and sometimes customize them for their partners.

Oppositely, Open or Public APIs are completely open for the access and share. Users get the chance to experience the same API in many ways, as each one of them is adding up the unique functionality to an API. One specific API type here grew up from a partner API model. In this model, businesses cooperate and share data or services. They also can allow access for the third party partner.

We should mention data APIs here, as they are serving internal data stores or fundamental data from SaaS app. Internal services APIs expose internal services and reflect complex actions and internal processes. External services APIs bring additional value to the existing company services. User experience APIs help the developers to create an API that will provide the best user experience through different device – mobiles, laptops, tablets, desktops etc.

API types

Web services, data structure, programming interface, operating systems – they all use a different type of API. This classification defines the interaction between systems or software and builds a specific architecture. Developers can use one API type and manipulate the resources in order to boost its functionality.

Types of web services that are most used:

  • XML,
  • SOAP,
  • JSON,
  • REST.

SOAP defines the structure of the messages and methods of communication. XML is older than SOAP. It functions through simple calls and uses less bandwidth. SOAP and XML use different types of support. JSON is similar to XML but uses JSON instead of XML. REST is different than the first three types, as it is an architecture actually. It enables simplicity and manipulation of the resources through the interface. REST consist nouns primarily and reflects logical data categories.

Web APIs can also be dived through client and server’s perspective, depending on how do they extend their functionality within the browser. Server-side executes functionality before the data transaction, while the client side manipulates numerous aspects of a browser.


As you can see, there are many classifications of APIs. Each one of them has one or more subcategories, which makes things more complex. However, if you want to design a good API, make sure you know not only what the API is, but its categories also.



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