API testing: How to do it intelligently

AFour Technologies
4 min readOct 27, 2020


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Testing plays an important role in the development of any software. Without testing, developers would be unable to ensure that the software is usable.

As a result, it is an industry-standard for any piece of software to undergo several rounds of rigorous and repeated testing. Both fully-fledged applications and software modules that support such applications must be included in the testing process.

The same goes for APIs or Application Programming Interfaces. The APIs have commonly used components for many of today’s most popular applications and platforms. With APIs now incorporated into the design of most applications, it is fair to say that they are rigorously checked like every other form of software.

In this article, we explain the importance of API testing to ensure that applications are ready to be shipped and our suggestions for the top three API testing tools that can be used to perform API testing smartly.

What is API testing?

The API stands for Application Programming Interface. You may think of an API as a brain that has several neurons stimulated by certain impulses. Any organization may build an application that sends the impulses to a public API and receives a particular response. This allows for smooth communication and sharing of information between various software systems of many software companies.

The mobile app from Uber is an exceptional worldwide example of how developers use APIs to incorporate other companies’ features. The app itself cannot calculate the route if you book a ride with Uber. Rather, it calls the Google Maps API and waits for a response. The entire process is so seamless that the user feels everything is happening right in the app.

API testing aims to ensure that APIs and their integrations perform as optimally as possible and that the server and client are not compromised by any bugs.

API testing best practices

API Testing has become such a significant part of the software development process. Thanks to modern API testing tools, it is becoming increasingly easy to perform complex API tests. But even the best tool in the world is only as good as its users, which is why it is important to be aware of the best practice of API testing:

  • Tests may fail for a variety of reasons, such as defective features, environment failure, or a version discrepancy between the product and the test, so writing tests from a debugging perspective in mind is very important.
  • Create your tests to run under various SUT configurations (System Under Test). Flexible evaluations can help respond to product development demands in the real world, for example when a client request results in a version split.
  • You need to know what you should not test. For example, it is hardly a good idea to check out the features of third-party apps, e.g., when dealing with an integrated payment processing gateway on a shopping application.
  • Always remember to add load to the system when checking for invalid parameters and unexpected problems, your goal should be to optimize your API so that no matter what you throw at it will gracefully fail.
  • Whenever possible, automate your tests. API test automation plays a far greater role than ever before in today’s fast-moving software development environment. In the next two years, it is predicted that the amount of API test testers who automated their testing will increase by 30%, partially due to the growing availability of superior API test tools.

Popular API testing tools

  • Postman

What began as a Chrome browser plugin is now a full API test solution that is being used by 5 million developers and more than 100,000 companies worldwide. You can add test scripts to requests and integration test suites or use scripts to transfer data between requests for APIs just to provide some examples of Postman Collections. Postman Collections are executable API descriptions that allow you to group and organize individual requests into folders.

  • SoapUI

SoapUI is the most common automated API test tool that covers anything from web service inspection to development, functional testing, and load testing. SoapUI offers comprehensive scripting options, using both Groovy and JavaScript, allowing the development of complex scenarios and customized functionalities.

  • Katalon Studio

Katalon Studio is a free, cross-platform API testing tool based on the Selenium and Appium open-source automation frameworks. It provides a specific keyword-driven approach to API testing and an easy-to-use user interface with an integrated development environment (IDE). Katalon Studio is available for Windows, macOS, and Linux, and there is also a browser add-on for capturing user activities in web applications and creating test scripts called Katalon Recorder.

Final Thoughts

Although there is no one-size-fits-all solution to test an API, there are certainly good practices that you should always bear in mind. Modern API testing tools make it simple to run and automate the complex API tests. AFour Technologies’ unique approach innovations to API testing will save you time, resources, and time for manual regression testing by using the latest testing tools and approaches.

Schedule a discussion with our Test Automation Experts today!



AFour Technologies

AFour Technologies is an ISO ISMS 27001:2013 certified organization that offers turnkey Software Product Engineering Services.