How to Monitor APIs That Return 401 or 403 Errors

401 and 403 are not the same

HTTP 401 generally indicates that authentication credentials are missing or invalid. HTTP 403 means the server understood the request but refuses to authorize it. Both can be legitimate security responses, but both can also signal a broken integration when your monitor should have access.

Why a monitor can create false alarms

If your endpoint requires authentication and the monitor sends a plain GET request, a 401 response may only prove that the monitor is configured incorrectly. The right test reproduces the required authentication path.

Use the correct headers

Authenticated API monitoring commonly requires an Authorization header and sometimes additional tenant, content-type, or version headers. PingStag supports custom headers for paid API monitors so the request can resemble the real client flow more closely.

Security matters

Never hard-code live credentials into article examples. Use placeholder values, rotate secrets regularly, and store real credentials in protected configuration rather than source control.

Interpret the result carefully

A 401 can mean “credentials expired.” A 403 can mean “permissions changed.” Neither should automatically be treated as infrastructure downtime without considering what the monitor is designed to authenticate against.