API tests are useful to help you proactively monitor that your most important services are available at anytime and from anywhere. API tests come in four different flavors that allow you to launch requests on the different network layers of your systems:
If your service starts answering more slowly, or in an unexpected way (for example, unexpected response body, wrong A record, etc.), your test can alert your team, block your CI pipeline, or even roll back the faulty deployment.
Note: API tests are single requests executed against your services. If you want to monitor sophisticated business transactions at the API level or endpoints that require authentication, you can also chain your requests using Multistep API tests.
Additional helpful documentation, links, and articles: