How to choose between UI and API Testing

Do you find it strange that every day customers are looking for new features?

How do you manually test each feature every time you make a change? It’s not easy. However, a lack in testing can lead to a failure of quality control which in turn leads to customers losing trust.

What’s the solution? API and UI testing.

What is the difference between API testing and UI testing? API testing can be used to verify that the web API responds correctly to client applications’ requests. UI testing can be used to verify that the user interface works as it should.

This article will help you learn how to use API testing and UI testing to create more reliable, robust code.

Read also: Beta Test vs Alpha Test

What is API testing?

APIs (application programming interfaces) are essential for any web application. They are increasingly important to developers. APIs enable applications to communicate with one another. They are an essential part of mobile app development. Developers must be able to test their API endpoints.

API testing is the process by which an API’s functionality can be verified. This involves verifying that the API can be accessed, returns correct data, and handles errors correctly. API testing also checks the business logic in your application.

API Test cases can also be covered:

  • Functional testing
  • Performance Testing
  • Security Testing
  • fuzz testing
  • penetration testing

It is the process of testing APIs to verify the functionality before you make it available to the public. This helps to ensure that your application runs as it should. You can also avoid many problems.

Quality assurance is only possible if API testing is done correctly. The API layer may not function correctly if it isn’t tested properly. Knowing how to test APIs has never been more important as more applications use them.

Your APIs can be tested manually or automatically. Many developers who create an API for a website don’t know how to automate API testing. This is a big mistake as you won’t know if your API works as it should. This will make it difficult to create a good, -free API.

What is UI Testing?

There are many tools and techniques available to test web applications. UI testing is the most popular testing method.

UI testing involves testing the functionality of an application’s UI. QA engineers usually verify that all elements of the user interface work as intended and that users can interact with the program in the right way. It is functional test.

You can either do UI testing manually, or you can use automated testing tools.

Manual Testing: This is the most common testing method. This involves manually testing a website or web app using a set test cases. Manual testing involves several steps, including the creation of a test plan, writing test case, and finally, execution on the target system.

Automation testing: This is a fast and efficient way to automate your testing process. Automated testing starts with identifying the objectives of the task and choosing the right tool. Once you have chosen a tool, it is possible to automate your tests. Selenium is the most used tool for UI testing. This tool can be used to automate tests on all browsers, including Chrome, Safari and Firefox.

Comparison of API testing and UI testing

Both API Testing and UI Testing can be essential parts of software testing. However, they are very different. API Testing focuses on the functionality of APIs while UI Testing focuses more on the usability and functionality of the user interface.

API testing should be done before UI testing to catch the majority of errors.

UI testing is still required to verify that the interface functions as intended. UI testing can be used to test specific cases such as when the interface is prone to errors.

Below is a table that shows the differences between UI and API test automation.

Compared toAPI TestingUI Testing
FunctionalityThe business logic functionalityThe functionality of both the UI as well as the business logic
FragilityPossibly fragileFragile
Speed of executionQuickSlow
Maintenance costsMediumHigh
Who creates themTesters and developersTesters

It becomes more difficult to ensure that software works correctly as applications become more complex. The tester must ensure that the product meets both the user’s expectations and the business needs. Overall, the user experience should be positive.

Despite all the testing, mistakes in software development still exist. It is important to include multiple testing methods in your test automation pyramid.

What tools can you use to test APIs?

You can test an API in two ways: manually or automatically. Because you can examine the API data, manual testing is very helpful for developers. Manual testing can be very time-consuming and not as useful for production purposes. For production purposes, you will need an automated tool to test your APIs.

Postman is a popular tool for API testing. You can create a URL and then send HTTP requests to your API. This powerful tool is very useful and you can do many useful things with it. Postman can also be used to automate testing, but this takes more time and effort.

API testing tools:

  • Postman
  • Katalon Studio
  • SoapUI
  • JMeter
  • Rest Assured

What tools can you use to test UI?

Developers have always tested and built web applications with a single tool: a browser. As the web developed, the types of testing needed to make sure that applications are ready for release changed. Selenium is one of the most used testing tools. It was created to test web applications.

These are the tools that you can use to test UI design:

  • Selenium IDE
  • Katalon Studio
  • TestComplete
  • Squish
  • Parasoft Selenic

What are the disadvantages of API testing

API testing has many benefits.

  • Before releasing your API to production, you can test its functionality. This allows you to easily test your application and make sure it works as intended.
  • Quickly test different versions of your API. Do you have different versions of your API? It’s no problem. No problem. You can write and run multiple versions of the test at once.
  • It is possible to test different features and functionality within a short time. All the endpoints can be tested in one go. Automate the testing process to create a test suite you can use regularly.
  • API Testing provides an overview of your APIs. It will help you understand the purpose of your APIs and how they were designed.

In short, API testing helps you improve your APIs’ quality.

What are the benefits to UI testing?

Testing the interface ensures that your software users have a positive experience. This can be done manually or with automated tools.

There are many benefits to UI testing. You can test the interface to make sure it is easy to use and intuitive. It is also possible to ensure that the software doesn’t crash or freeze. It is also possible to ensure that the software conforms with accessibility guidelines. You can also ensure that the software works well with different operating systems and devices.


More companies are realizing the importance of quality control and testing of applications.

Software testing is an important step in any software development process. Software testing can identify potential bugs or errors that could lead to a program’s malfunction. It can help you pinpoint the areas of your program that require improvement. It can also help you determine the best way to show your software to users.