The Different Kinds of APIs and Web Services: A Summary


If you’re new to the world of software development, then you may have a lot of questions about a certain three letter acronym, namely API. API stands for Application Programming Interface, and it is a very significant part of modern software development. This is because the use of APIs allows developers, even those with limited experience writing code, to build their software more easily and efficiently than ever before.

In this article, we’ll be talking about what exactly is an API, what different kinds of API and web services exist, and how the two differ from each other.

What is an API?

Simply put, an API is a software component that standardizes the way one application or program can communicate or interact with another. Such interactions may include one application requesting access to data that another application is holding or the former invoking certain features from the latter to perform its main function. 

A real-life example of this in action is when a user can copy and paste a block of text from a word processing program, such as Microsoft Word, into a text box on their browser of choice.

What makes APIs so useful?

APIs are very useful to software development in general because they standardize the way applications can talk to each other. This significantly cuts down on the amount of coding a developer has to do when building their software.

Instead of that developer having to code various interfaces for their application to be able to interact with other specific applications, all the developer has to do is to procure the APIs of those applications and then implement them into their code. This procurement may involve asking for permission or paying a fee, but the result is the same: seamless communication and interaction without the coding work usually required for such a feature.

Certain events in the API coding scene are encouraging this collaboration between developers. One such event is the emergence of the OpenAPI Specification or OAS. By using an OpenAPI specification toolkit to create their API, a developer will be able to take advantage of this in specific ways. For instance, this will not only make them more efficient in software development, but also make their final products more user-friendly. Other benefits include automatic API documentation generation, automated testing, fast prototyping, and more.

What are Web Services?

A web service is essentially a different type of API. They perform the same function, except that they deal with applications that require an online connection to communicate with each other. A real-world example of this is Twitter’s API being used by WordPress to allow its bloggers to display their Twitter profile on their sidebar.

Since they are very similar to APIs, the overall significance and usefulness of web services stem from how they help developers build their web applications more easily and efficiently.

Now that we know what APIs and web services are, let’s go over their respective types.

Types of APIs

  • Open APIs: APIs of this variety are also known as public APIs. As their name suggests, the general public has free and unrestricted access to them. Anyone can download them and integrate them into their projects in whatever fashion they wish.
  • Partner APIs: This type of API is generally not available to the public. If a developer wishes to use a partner API in their project, then they must seek permission from the API owner, either in the form of specific rights or licenses.
  • Internal APIs: The opposite of Open APIs, Internal APIs are strictly exclusive to the company that owns them and are only meant for use inside the company’s network or workplace setting. Internal APIs are used specifically to improve a company’s in-house products before they are released to the public.
  • Composite APIs: This type of API is essentially two different types of APIs combined as one, such as a service type API and a data type API. It takes the form of a sequence of tasks that run at the same time as a result of another specific task being executed. Composite APIs are used mainly to speed up and improve the performance of certain interfaces.
  • Web API: This type of API is also known as a web service. It facilitates communication between two specific online applications through HTTP.

Types of Web Services:

  • SOAP: SOAP stands for Simple Object Access Protocol. This web service uses XML, or eXtensible Markup Language, as a format for transferring data. As it is essentially an API, it also defines the structure of the messages between two online applications and the method of communication between them. It is known for having very strict rules and advanced security and is heavily function-based. As a web service, SOAP is also known to require more bandwidth than other web services.
  • XML-RPC: This web service is similar to SOAP in that it uses XML to transfer data. However, unlike SOAP which uses a proprietary format of XML, XML-RPC uses a specific format. It is also considerably much simpler and less bandwidth-intensive than SOAP.
  • JSON-RPC: This common type of web service shares similarities with XML-RPC in functionality. However, instead of using XML, it uses JSON, or JavaScript Object Notation, to facilitate the transfer of information. As a result, JSON-RPC is lightweight and significantly easier to use than its XML counterpart. The tradeoff here is that this web service only supports text and numbers and has lower security.
  • REST: REST is different from its other fellow web services in that it is not a protocol by definition. Rather, it is a set of architectural constraints that allow for much simpler and easier development of web services. These constraints include having a simple interface, resources being easily identified and manipulated through HTTP, and others.

APIs: a crucial part of modern software development

While seemingly minor in the grand scheme of software development, APIs perform a very important function: to facilitate the seamless and standardized communication between two separate software applications. This function has not only given rise to an entirely new method of software development, but has also contributed significantly to the ongoing collaboration between developers from all over the world.

As such, all developers need to learn as much as they can about APIs, so that they are able to fully understand the advantages of using them and perhaps even start developing an API of their own in time. There are many available API development tools like those on Stoplight that can help you achieve your goals.


Author: I’m  Jaylin: SEO Expert of Leelija Web Solutions. I am a content manager, and the author of and a full time blogger. Favorite things include my camera, travelling, caring my fitness, food and my fashion. Email id:


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