API Testing Checklist and Best Practices

API testing check list: 

1. Check the response status code, first.
2. Verify whether the necessary response headers are present.
3. Confirm the response body's content.
4. Check for proper error handling and response codes.
5. Verify how inputs that are empty or null should be handled.
6. Examine the API's performance and response time.
7. Check for security flaws including cross-site scripting and SQL injection.
8. Check for correct concurrency and load handling.
9. Examine compatibility with various platforms and devices.
10. Check that edge cases or invalid input are handled correctly.

Best practices for API testing: 

1. Give testing the top priority based on how crucial the API is and how it is used.
2. Employ automated testing methods to boost productivity and lower errors.
3. Before releasing to production, extensively test the API in a staging environment.
4. Employ both manual and automated testing.
5. Use test-driven development to make sure all tests are covered.
6. Separate the testing environment from the development environment.
7. Track and report issues and bugs with the appropriate documentation.
8. After deployment, continuously check to see if the API is operating as intended.
9. To find and address vulnerabilities, use security testing tools.
10. Run edge cases and a variety of input types via the API.