Application Programming Interface - How It Works And How To Create Them

An application programming interface (often known as API) is a computing interface that can define interactions between multiple software intermediaries. You may be familiar with the APIs concept, or you may be even a developer who creates and deployed APIs on a daily basis.

But have you ever wondered: how exactly does an API work? Having fundamental knowledge changed the way software developers write applications, the technology introduces the simplicity and flexibility of operations that were previously only available to highly trained individuals

Let us explore APIs' precise functions and how they can significantly help your business users get more done at a faster pace, without having to learn coding skills.

*Note: Check out our “CMS Headless API-based Architecture: What Is It and Why Should You Invest In It?” to have a base knowledge of what API is.

How do APIs Work?

APIs act as intermediaries for two applications to interact. This software acts as a messenger that sends requests to suppliers, collects responses, and sends them back to the source of the query.

Application Programming Interface - How It Works And How To Create Them

What makes APIs so important is that they define functionalities that are not dependent on their own implementation. This means that if the definition and implementation are different, these functionalities don’t compromise each other.

In simpler words, APIs provide building blocks for which completely new programs can be developed. The API frees developers from having to rewrite any existing code, without having to use them over and over again, and without having to restart every time they edit the program. This improves their productivity greatly and gives them more creative without worrying about product features (including complete APIs).

How do APIs work in practice?

If you’re wondering how API works and achieves efficiency, there is a principle called API abstraction. This is an advantage because it allows the consumer application to be separated from the service infrastructure.  As long as the exact specification of what the operator provides to the endpoint is not subject to change, this prevents API-based applications from noticing any changes in the infrastructure behind the endpoint. 

This can benefit service providers in terms of flexibility, as they can customize services according to their needs. For example, the infrastructure behind the API (cloud-based and physical-based, data center-based virtual servers) can be moved at will without any consequences.

How useful is API?

Now, after we have answered: how does API work? Let’s get into what they can actually do. It is important to realize that the number of APIs available in modern browsers and the entire application is utterly huge, providing developers with a wide variety of coding objects to choose from. 

Among the most commonly used API(s) are REpresentational State Transfer (or commonly known as REST API), and GraphQL. Many tech giants like Facebook (using GraphQL), Google, Twitter, Instagram, GitHub, and so on are using REST APIs to allow third parties to access their public data. The following scenario usually occurs: you make a client-to-server call, and then retrieve the data over the HTTP protocol. For example, if you want to display the latest tweets from your Twitter account on your website, you can call Twitter’s API and it will return data containing your latest tweets. You’ve made your first API request!

However, when you make payments online, it is an API for processing credit card payments from Visa or Mastercard to your carrier. For example, it is also an API for getting flight prices comparison from multiple airlines.

The client-side storage API is another increasingly popular solution that allows data to be stored on the client-side, making it possible for the application to run offline or save its state between page loads. You can also reference the server to obtain the API, graphics API, audio and video API, and device API.

How to create an API

In order to build a new API, first, we start with a plan that will help determine the best tools to use for the job. Start with your goals and define the intended users. The API solutions should bring benefits and values to both your organization and your users. If you’re building a private one, users would be your colleagues, while for public APIs, you'll need to find out who your target audience will be. By understanding the needs of your users, you can determine the requirements and make sure a long-term success for your API.

The next step will be designing the API. Actions like separate API design into different layers, choose your architectural style, or think about security are essential.

Next, it’s developing your API. You can start by building API endpoints, handle exceptions and errors, use throttling, use hyperlinks for navigation to related resources, etc.

After finishing developing the API, you can test it. And it’s up to your priorities, you can run different types of tests like validation, functional, load, security, etc. But there are a few rules when it comes to API testing: you should use realistic data for realistic results, simulate errors and edge cases by changing responses, and don’t use live APIs for running testing. 

The final step is to monitor your API and go through the feedback for better improvement. 


Now that you understand what APIs are, why it is useful, and how to build it for your software development project. It’s time to apply these in practice. And if you need expert advice, drop us a line to get in touch with our expert team!

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