What is an API?

API stands for Application Programming Interface. In simpler words, APIs are stand-alone pieces of software that we send calls to and get the yield. Most developers deal with APIs every day. If you website uses login using Facebook, that is connected to Facebook API, if you save your files in Dropbox, that is an API and so on. As the importance of API development grows, we also realize that being able to test these APIs properly is a crucial task. With APIs, applications talk to each other without any user knowledge or intervention.

What is API Testing?

This is type of functional testing in which developer can test APIs. API testing is entirely different from GUI testing and mainly concentrates on the business logic layer of the software architecture. API testing uses software to send calls to the API and get the output. This (figure 1) represent the OSI model of API.

API Testing


Test Cases for API Testing

Test cases of API testing are based on


How to approach API Testing?

Following points helps the user to setup an API Testing approach:


What to test for in API testing?

API testing should cover at least following testing methods apart from usual SDLC process:


Types of Bugs that API testing detects


Tools for API Testing

There are some open-source tools for API Testing.


The Postman API has several endpoints to help you integrate Postman even more deeply with your development toolchain. You can add new collections, update existing collections, update environments, add and run monitors directly through the API. This API allows you to programmatically access data stored in your Postman account with ease.

Postman - get user audio

Postman - add category


it is Open Source Tool In which you can Test your APIs. The Main difference between SoapUI and other open source tools is that you can also perfume load testing of APIs



Karate DSL

Karate is a new test framework based on the well-known Cucumber library. It allows you to quickly write meaningful tests for web services using a domain-specific language (DSL).

Robo Hydra Server

Robo Hydra is a web server designed to help you test any kind of HTTP, HTTPS, or Web Sockets client


Hippie-Swagger tool is same as Postman. It is a tool for testing RESTful APIs.


API Testing Browser Extension tools

API testing Plugins are also available in web browsers such as Chrome and Firefox. Here are some tools which are available on Chrome Webstore.


Advantages of API Testing

Properly tested APIs are a breeze to work with and save a tonne of time over the course of a project.



API consists of a set of classes / functions / procedures which represent the business logic layer. If API is not tested properly, it may cause problems not only the API application but also in the calling application. We provide API development and testing services. We will provide document with results after testing your API.