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What is API (Application Programming Interface)?

Iveta Vistorskyte

2021-07-196 min read

API, which stands for Application Programming Interface, is an intermediary between different software and its primary purpose is communication between them. API delivers your query to the provider and then gives its response back to you.

Web API is an essential part of the digital world because this middleman between software helps to save a lot of time for developers. In this article, you’ll find an explanation of what an API is and how it works.

What exactly is an API?

API is a tool that allows different software components to exchange data. Application Programming Interface is the code that manages the access point (or points) for the server. The end-user doesn’t notice these exchanges on a website or an app.

Let’s provide you an API example to help you understand clearly what it is. Imagine that you own a training app. One day, you got the idea to provide your users with an ability to listen to music on your app while they exercise. For this idea to be implemented sooner, you can look for an opportunity to use a web API where your website’s server communicates directly to the music streaming app’s server. Your app can request to integrate a playlist directly to your training app and provide all the required music for your users.

In this case, your developers can save a lot of time by integrating required music streaming platforms rather than working hard by doing nitty-gritty work and, for example, collecting the world’s biggest playlist.

Most applications or websites nowadays use at least some third-party APIs. It’s just easier to use existing solutions rather than come up with new ideas that require a lot of effort and time.

By using APIs, developers can save a lot of time

How do APIs work?

Simply put, the software sends a request to the other system to access the data or provide a required service. A request can only access a system’s API layer (also called an endpoint). Usually, with a query, there is a requirement to provide an API key additionally.

What is an API key?

An API key or an Application Programming Interface key is a unique identifier used to authenticate requests to an API. Usually, API keys contain a string of letters and numbers that identify the website or app making the request.

What is API architecture?

API architecture is the procedure of defining the methodology and, eventually, developing a software interface that provides backend data and the needed functionalities for use in new applications. This architecture will allow you to create application ecosystems that are reusable and modular, which is a great solution for microservices. In order to take advantage of everything that web APIs can do for your business, it is essential to provide it with the right API architecture.

What are the different types of API architectures and protocols?

There are several different types of API architectures with REST, SOAP, RPS, and GraphQL being the most popular in today’s environment. Let’s learn a bit more about each of them.


REST stands for Representational State Transfer and is a software architectural style applied to modern web APIs. REST APIs, also known as restful APIs, allows for scalable, easy-to-use, and lightweight web APIs that can be used for transferring data from a web server to the client. 

One of the greatest advantages of REST architecture is that it provides a good amount of flexibility, which means it is suitable for different use cases, such as:

  • Web use

  • Cloud applications

  • Cloud services 


SOAP is an abbreviation for Simple Object Access Protocol and is the most widely implemented architecture for web services. This protocol strictly defines how messages are supposed to be sent and what they need to contain. Due to this particular feature, SOAP APIs are more secure than REST APIs but are also code-heavy and difficult to implement overall. 

The SOAP protocol is typically applied for company internal use (for example, internal data transfers that have to be performed at high security) or for specific services requested by trusted partners. 


In comparison to REST and SOAP protocols that only aid in the transfer of data structures, RPS (Remote Procedure Call) executes processes on a web server. These processes do not need to run only on a local machine, but can also be executed through remote networks.

Since RPS architecture is limited in its capabilities, it is not as widely used as SOAP or REST protocols. However, it can be successfully utilized for internal systems to perform basic requests, especially several different ones at the same time. 


Initially developed by Facebook in 2012, GraphQL became popular among tech companies over the years and got established as one of their main philosophies for web API design. 

This architecture gives users a possibility to describe their data requirements using a JSON-like format. By having control over data that has to be gathered, web API customers get the data they need faster and receive an optimized experience as a whole. GraphQL is used by teams of various sizes across different environments in order to power their APIs, websites, and mobile apps.

Types of APIs

It’s not a surprise that there are different types of APIs (Application Programming Interfaces), and we outlined the essential ones below:

1. Public APIs. These web APIs are accessible for every developer who needs to get some sort of data or use it as third-party software. Usually, these APIs may require registration or an API key. In any case, the purpose of these APIs is to make data or services available to any developer.

2. Partner APIs. Let’s think of a previous example of a training app and a required playlist on it. If you need services from other companies, you usually make a partnership with them by promising that it’s worth collaborating. For example, you can offer them additional traffic to their website (or application). In exchange, they provide you with partner APIs that you can integrate into your app. It doesn’t mean that their API will be available for other developers. There is usually a long process with a specific validation to access your partner APIs.

3. Private APIs. These Application programming Interfaces aren’t accessible for external users as they’re used in companies’ internal systems. Their primary purpose is to facilitate and improve internal development teams’ work.

4. Composite APIs. These APIs combine multiple API requests and send them to the server in a single API call, which leads to receiving one response. Using this type of API is a great way to save on data usage as well as improve the efficiency of your application by keeping the number of API requests at minimum.

There are different types of APIs

Can API act as a layer of security?

Before defining how an API can act as a security layer, let’s give you another example.

Imagine that you possess a music streaming app. You’ve got an opportunity to collaborate with a famous training app by allowing your services to be accessed through it. By providing an API or Application Programming Interface, your whole app’s data is not fully exposed to training app developers. Instead, your and the training app’s server communicates with small packets of data, only sharing what is essential. You’re in charge of what kind of data you want to deliver.

When you’re providing your web API for other apps or websites, you control what data is accessible. This is the reason why you can find information that API is explained as a layer of security. However, it’s not fully true.

The main idea of an API is to grant access to your data to other developers. Your exposure isn’t reduced by implementing an API. On the contrary, it’s increasing. On the primary purpose, web APIs are not used as additional safety layers. Think of your server as a house. If you want to show your neighbors a little bit of your home decor, you can mount a window. The neighbor won’t see the whole house, but a window is not an additional security measure that prevents, for example, from thieves breaking in.

APIs aren’t used as additional safety layers

Public APIs and API integration

With increased ubiquitous networking, an allocation of communications base and wireless technologies to ensure constant connection, more public APIs have become accessible. The process of writing code and interacting with other sellers’ code online is called API integration. 

You should bear in mind that “public” does not indicate that it doesn’t cost anything. Yet, the vast accessibility of public APIs results in much easier integration. 

Oxylabs provides a public Residential Proxy API for easier proxy management. When using this API, you can:

  • Create, update, and delete sub-users’ accounts 

  • Control traffic limits for each sub-user 

  • Get statistics about traffic usage

Note that in one account, you can have up to three sub-users.

It’s a time-saving solution to get sub-users’ information that you require in seconds.

Oxylabs Web Scraper API

Oxylabs also provides a Web Scraper API, supported by a proxy infrastructure and maintained remotely by professional developer teams. It’s a customized scraper, just like our SERP Scraper API and E-Commerce Scraper API, designed for data retrieval operations on a large scale.

Our Web Scraper API is a suitable choice for gathering public data from most of the websites.

Wrapping it up

API (Application Programming Interface) is an essential part of the tech world. The use of web APIs saves a lot of developers time and resources. They can focus on more critical tasks and devote their time to developing new technologies rather than thinking of creating something that is already made.

If you’re interested in how to extract data from any website or what a proxy server is, feel free to check out our other blog posts.

About the author

Iveta Vistorskyte

Lead Content Manager

Iveta Vistorskyte is a Lead Content Manager at Oxylabs. Growing up as a writer and a challenge seeker, she decided to welcome herself to the tech-side, and instantly became interested in this field. When she is not at work, you'll probably find her just chillin' while listening to her favorite music or playing board games with friends.

All information on Oxylabs Blog is provided on an "as is" basis and for informational purposes only. We make no representation and disclaim all liability with respect to your use of any information contained on Oxylabs Blog or any third-party websites that may be linked therein. Before engaging in scraping activities of any kind you should consult your legal advisors and carefully read the particular website's terms of service or receive a scraping license.

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