Your API returns 200. Does that mean it works?
From a reachable endpoint to a usable service. Check response meaning, latency and dependencies as well as status codes.
The endpoint check is green, but a customer cannot load their data. The server accepted the request and sent a response while the business function remained broken. An HTTP status is an important signal, not a complete test. Useful monitoring starts with what a client needs from the API and what can realistically fail.
Separate a live process from a ready service
A simple liveness check may succeed during a database outage. A readiness check instead determines whether an instance can serve traffic. These checks have different purposes. Treating every external dependency failure as a dead process can trigger unnecessary restarts across all instances.
Keep health endpoints inexpensive and free of sensitive information. Public responses should not reveal passwords, internal topology or user records. Detailed diagnostics belong in a protected environment.
Verify the meaning of the response
Check the expected status, content type and a suitable stable part of the response. Some applications return an error inside JSON with status 200. Others return an HTML login page instead of JSON. A basic uptime check can treat either as success even though the client cannot use the result.
Choose a representative, safe operation
Pick a read that exercises an important path through the application and database. Use a dedicated test account with minimal permissions and stable test data. A monitor must not create real orders, message customers or modify production records on every check.
If you need to test writes, prepare a separate scenario with cleanup and clear oversight. Secret tokens must not appear in URLs or public repositories. Include credential rotation in monitor maintenance so an expired permission does not masquerade as a service outage.
Watch latency and errors, not just the average
A successful response after a long wait may still be unusable. Choose a latency threshold based on the endpoint's purpose and follow its trend. Internal percentile measurements complement external checks by exposing the slow tail of requests that an average hides.
- Reachability and the expected HTTP status.
- Response content type and meaning.
- Latency and client time limits.
- An important, safe customer journey.
What to take away
Start with one useful test of the API's main function. Keep a cheap healthcheck as a supporting signal; build confidence around a result the client can actually use.
