First of all, we’ll see what is an API. API stands for Application Programming Interface. It contains set of rules which facilitate programs to communicate with each other. This picture clearly shows the functionality of APIs.

An API allows us to get data from outside sources.

The word REST stands for REpresentational State Transfer. REST architecture is followed by the developers when creating APIs on servers. When creating REST API, there is no need to install any additional software or libraries.

REST can handle multiple types of calls and return data in different formats. The client and server should be independent from each other as a requirement.

For an example if we go to the website of an online store selling mobile phones and search a specific category by our choice, REST APIs are used to query the store’s database. Then only the relevant result with mobile phones of customer’s choice is parsed into the website via the API call.

All these REST API calls need to be implemented in the backend part by the developer.

To build RESTful API we need,

• A server
• A database to store data.
• A backend part containing written APIs

These languages are the best for writing RESTful APIs.

We can check the written API by using many tools. Some are listed here,

1. SoapUI
2. Katalon Stidio
3. Postman
4. Tricentis Tosca
5. Apigee
6. JMeter
7. Rest-Assured
8. Assertible

Let’s see a sample REST API written using Laravel framework.

This is a method implemented within a controller. It queries required data from the database and returns as json. We can check the json output using Postman. Here is the output.

Then, we can get this json output into any web or mobile application by converting it into a required format.