There are 9 types of API testing :
1.Smoke Testing:
This is done after API development is complete. Simply validate if the APIs are working and nothing breaks.
2.Functional Testing:
This creates a test plan based on the functional requirements and compares the results with expected results.
3.Integration Testing:
This test combines several API calls to perform end-to-end tests. The intra-service communications and data transmissions are tested.
4.Regression Testing:
This test ensures that bug fixes or new features should not break the existing behaviors of APIs.
5.Load Testing:
This tests applications' performance by simulating different loads.Then we can calculate the capacity of the application.
6.Stress Testing:
We deliberately create high loads to the APIs and test if the APIs are able to function normally.
7.Security Testing:
This tests the APIs against all possible external threats.
8.UI Testing:
This tests the UI interactions with the APIs to make sure the data can be displayed properly.
9.Fuzz Testing:
This injects invalid or unexpected input data into the API and tries to crash the API. In this way, it identifies the API vulnerabilities.