1. Test for Core Functionality
API testing allows accessing the application without the UI (User Interface). The core functionality of the application is tested before the GUI tests. It helps in identifying the minor issue which can become bigger during the GUI testing.
2. Time Effective
API Testing does not need GUI to be ready. It can be performed earlier in the development cycle. API testing is less time-consuming than GUI testing. API tests offer test results quickly. They significantly accelerate development workflows. This helps in speeding up the feedback loop and identifying issues faster.
3. Reduced Cost
API testing requires less code and provides better and faster test coverage compare to GUI test automation. You can identify issues at an early stage. It is easier and comparatively inexpensive to fix the issue at the early stages. This reduces the cost of the testing project.
4. Language-Independent
The data in API testing is exchanged data using XML or JSON. These transfer modes are completely language-independent. It means that you can select any core language when using automated testing services for the application.
5. Easy Integration with GUI
API testing allows highly integrable tests. This is useful if you plan to perform functional GUI tests after API testing. For example, simple integration will allow for the creation of new users within the application before the start of a GUI test.