API testing vs UI Automation Testing: Which to prefer for testing the business logic of the application

For a QA team that takes on the Agile methodology for its project, the biggest challenges are tight deadlines and changes in user requirements as the sprint progresses. These changes often range from GUI elements to business logic alterations. Keeping this in mind, a QA personnel must be very critical when selecting the testing technique. They need to ensure that they can yield the required results in a time-efficient manner through the selected methodology.

QA personnel can use many different testing methodologies based on their project needs. Examples of testing methodologies include manual testing, performance testing, automation testing, API testing, etc.  

In this article, we will discuss the automation and API testing methods and which method to prefer when the business requirements are changing rapidly. 

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What is API testing? 

APIs are the communication medium between different applications and contain the business logic of an application. The API takes requests from a client system to the web server and from a web server to the client machine.  

The API testing methodology tests the business logic of an application by sending different calls using specialized software and verifying the system’s response. These calls usually validate the CRUD (Create, Read, Update, Delete) operations. Besides validating the response code, API testing is used to validate the application’s business logic. 

What is UI Automation testing? 

In UI Automation testing, specialized tools are used to validate button clicks, navigations, data entries, different UI features, application flows, and it also enables communication between the end-users and the application’s UI elements. 

Comparison between API Testing and UI Automation Testing: 

For testing the application’s business logic, many organizations follow the UI Automation test frameworks, but it can be challenging when the requirements are changing continuously. Let’s first discuss some of the drawbacks of the UI Automation tests, and then we will discuss the benefits of performing the API tests on the application. 

  1. Drawbacks of UI Automation tests: 
  • Limited test coverage 
  • Slow Execution Speed 
  • High Maintenance Cost 
  • High Fragility 
  • Time-intensive process 

      2. Benefits of API tests: 

  • Low maintenance cost 
  • Fast Execution Speed 
  • Low fragility 
  • Pre-production testing method 


In the software testing industry, UI Automation and API testing go side by side. With API testing, the functionality of the APIs is verified, while in UI Automation testing, the focus is more on testing the functionality of the user interface. So, suppose the requirement is to test the business logic of an application, in that case, we can safely prefer the API testing method over the Automation UI testing because of its low fragility rate, fast execution speed, and low maintenance cost.