What is an API?

Api Full-Form, Meaning, Definition, Types & Example

Application Programming Interface (API) is defined as a software interface that allows two applications to interact with each other without any involvement from the user. API is a combination of software functions and processes. In simple words, API can be defined as a software code that can be accessed or executed, enabling two different software to communicate and exchange data with each other.

API example 1: 

Let’s consider an example to understand the function of an API:

Let’s use a simple daily life example to study the working of API. Imagine that you went to a restaurant to take lunch or dinner. The waiter comes and offers a menu to take your order. gives you a menu card, and you will be provided personalized order if you want your sandwich to be without onion.

After some time, you will receive your order from the waiter. It is to be observed that something happens in between before you receive your order. The waiter plays an important part as you will not go to the kitchen to take your order nor will give the kitchen staff the details about your order.

API also does the same by taking your request, and like the waiter tells the system what you want and then provides a response back to you.

API Example 2:

Let us see more technical examples.

For instance, you go to the movie site, enter the movie, name, and credit card information, and then print tickets.

Here collaboration with other applications takes place. This integration is known as “seamless,” because you don’t have a clue when a software role is passed from one application to another.

What is the need for an API?

Below are some reasons for using API:

  • Application Programming Interface acronym API enables two different software’s to communicate and exchange data with one another.
  • It allows the embedding of content from any site or application more efficiently.
  • APIs can access app components. The delivery of services and information is very flexible.
  • The content generated is published automatically.
  • Customization of the content and services used by the user or company is available.
  • APIs help to anticipate software changes.

Features of API

Some important features of API are:

  • It provides valuable services like data, function, audience).
  • It helps in designing a business model.
  • Simple, flexible, adaptable.
  • Managed and measured.
  • provides developer support.

Types of API

There are four main types of APIs:

Open APIs: These types of APIs are publicly accessible to use like OAuth APIs from Google. It has no restrictions. Therefore, they are also called Public APIs.

Partner APIs: To access this type of API, specific rights or licenses are required. They are not available to the public.

Internal APIs:  They APIs are internal or private. These APIs are developed by companies to use in their internal systems. It helps in enhancing the productivity of teams.

Composite APIs: This type of API combines different data and service APIs.

Communication level of APIs:

Communication levels of APIs are:

High-Level APIs:

High-level APIs are those that are used in REST form, where programmers have a high level of abstraction. These APIs have limited functionality.

Low-Level APIs:

This kind of API offers a lower level of abstraction, which means they are more detailed. It enables the programmer to manipulate functions within an application module or hardware at a granular level.

What are Web APIs?

A Web API is defined as an application programming interface that is used either for the webserver or a web browser.

Two types of Web APIs are:

1. Server-side:

Server-side web API is a programmatic interface consisting of one or more publicly exposed endpoints to a defined request-response message system. It is expressed in JSON or XML

2. Client-side:

A client-side web API is a programmatic interface that helps to extend functionality within a web browser or other HTTP client.

Examples of web API:

  • Google Maps APIs enable developers to embed Google Maps on webpages by using a JavaScript or Flash interface.
  • Developers can integrate YouTube videos by using YouTube API.
  • Twitter offers two APIs. The REST API allows the developers to access Twitter data, and the search API generates methods for developers to interact with Twitter Search.
  • Amazon’s API provides developers access to Amazon’s product selection.

API Testing tools

Here are some popular API tools:

1) Postman

Postman is a plugin in Google Chrome and is used for testing API services. It acts as a powerful HTTP client to check web services.


  • Enables all modern web API data extraction.
  • Allows you to write Boolean tests within Postman Interface
  • A collection of REST calls can be created and each call can be saved as part of a collection for execution in future
  • Postman is more reliable for transmitting and receiving REST information.

link: https://www.postman.com/

2) Ping API

Ping-API is API testing that allows writing test scripts in JavaScript and CoffeeScript to test your APIs. It allows inspecting the HTTP API call with complete request and response data.


  • Ping- API to schedule tests every minute or hour
  • Supports writing script to set request headers, body, and URL parameters.
  • Provides validation for CRUD flow and log in to Ping API

Link: https://ping-api.com/

 3) vREST

vREST API tool gives an online solution for automated testing, mocking, automatic recording, and specification of REST/HTTP APIs/RESTful APIs.


  • It consists of an exhaustive tool to validate your REST APIs quickly.
  • Deliver zero-defect web applications with less effort in API testing.
  • Allows validation of web applications.
  • Generate’s documentation for your API specifications.

Link: https://vrest.io/

Application of API

Here, are some Applications of API:

  • Batch Distribution / Drive Traffic.
  • Expand Footprint.
  • Feature Development
  • Explore New Business Models.
  • Content Acquisition Advance Business Model.
  • Internal Content Distribution / Innovation.

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