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API Testing Tutorial: How to Perform API Testing?(Types & Tools)

By February 4, 2021August 23rd, 2023No Comments5 min read
API Testing Tutorial: How to Perform API Testing?(Types & Tools)

What is API Testing

 API testing is the process of determining the efficiency of an application. Every app consists of several layers that make it a complete application. The primary layers of an application are the presentation or user interface, database, and business layer. Out of these, the database layer is preferable for manipulating and modeling the data. So, Today our API Testing tutorial for Beginners will go through the basics of API Testing

API Testing is performed mostly on the application’s business layer, where the logic is processed, and business operations are carried out. The business layer handles all the user interface & database transactions within the application.

API Testing is destined to check all the in-depth programming aspects of an application to ensure its streamlined functionality and performance. To better understand how the API testing is performed, you must know the types and tools used for commencing with this job.

What are the Different Types of API Testing?

Do you want to know what are API testing methods or types? You definitely should know them because you cannot know their execution method without understanding the different types of API Testing. Therefore, here are the various types of API testing executed upon the application:

  • Functional Testing 

Functional testing is meant for testing the selected functions of the application based on the codes. The API functions are to be tested with specified parameters to ensure that they function well within the application after it goes into the targeted audience’s hands.

  • User Interface Testing

User Interface testing is meant to examine the easy accessibility of the application for the users. This test focuses on the interface that holds onto API. Moreover, this test will give a verdict on the usability, health, accessibility, and efficiency of the application as a whole.

  • Security Testing

Security testing is essential within the API testing practices to ensure that the app is safe from external threats. Some of the aspects that are checked within the security testing services are encryption validation, API design for access control, user rights management, and others.

  • Load Testing

Load testing is imposed to make sure that the entire codebase has the potential to withstand heavy load. All the theoretical assumptions in terms of the load-bearing capacity of the application are also monitored. Hence, load testing is used to check the performance of the application in both normal as well as peak conditions.

  • Runtime & Error Detection

Runtime and error detection is to define the actual API running potential. This testing technique is meant for monitoring the app performance, executing the errors, resource leaks, error detection, and other such aspects. The detected errors will be rectified and fixed to ensure that there will be no runtime breakdown.

  • Validation Testing

Validation testing is mostly for the final steps of API Testing, which is meant for the development process. This testing process is carried out to verify the product, behavior, efficiency, and other such aspects of the application. Hence, this testing assures that the application is correctly developed.

  • Fuzz Testing

Fuzz testing is to determine the security audit by identifying any negative behaviors or forced crash situations. This test is determined to ensure that the API limits are optimal for tackling the worst-case scenarios.

What are the Tools used for API Testing?

The answer to this question in your mind is that there are many proficient tools available in the market for API automation testing. like REST API testing, Postman API testing, etc. Professional Web API testing service providers and testers are using these renowned tools to commence with the API testing aspects. Some of the essential tools are:

  • SoapUI- SoapUI is one of the popular functional testing tools that is meant for addressing API testing. It is intended for testing REST, SOAP, and other such APIs without much hassle.
  • Katalon Studio- Katalon Studio is a free automation tool for conducting API tests. This tool is best for API, Web, and Mobile applications. 
  • Apigee- Apigee is a cross-cloud API tool used for testing the build and the performance of the API to ensure the efficiency of the application. 
  • Tricentis Tosca- This tool is compatible with DevOps and Agile and offers a plethora of benefits. It is a continuous testing system that is embedded with automation for commencing resilient testing across different stacks. 

Important Read: Postman API Testing Tutorial

These are just a few of the many efficient tools available for conducting the API testing job. You just need to make sure that you are picking the right team of professionals who are equipped with the right tools and expertise for commencing with your API testing needs.

With professionals’ help, you can expect efficient and speedy API testing services, thereby eradicating all the minor bugs and errors within the application. Now, you can go ahead and check on the execution of API testing.

Process To Understand How To Perform API Testing?

If you want to know what are the steps/process to perform API testing, then here are some of the guidelines that people must keep in mind to know about how to perform API testing. The steps include:

  • Firstly the testers need to understand the in-depth API requirements. For instance, the purpose of API, the workflow of the app, etc.
  • Primarily, the testers will focus on testing the small functional APIs and then organize their endpoints of them.
  • With the automated tools, the testers can leverage the potential of automation testing for API. You must have to pick the right automation tool for enhancing the automation testing capability of API.
  • Verification methods must be chosen to ensure that the API potential is improved.
  • The testers need to specify the API output status, like whether the output status in terms of response code is equal to 200 or not. It is essential for the testers to decide whether the testing is a pass or fail.


As per our API Testing tutorial, These are a few of the essential types, tools, and processes that are combined together to conduct API testing. Reach out to professional Web API Testing Companies that have skilled experts to conduct such tests with assured outcomes. You just need to make sure that you are well aware of what to expect from your application for a successful business outcome. You can then look out to hire API tester to meet your specific requirements.

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