Monitoring Your API: Why an HTTP 200 Isn't Always 'Healthy'

"200 OK" Can Still Mean Broken

If you run an API — or a site that depends on one — you've probably assumed that a 200 OK response means everything's fine. Often it does. But not always. A server can happily return a 200 while serving an error page, empty data, or a maintenance notice. Real monitoring goes a step further. (For a refresher on what each code means, see HTTP status codes explained.)

Why Status Codes Aren't the Whole Story

Consider these very common failures that still return a 200:

• A misconfigured load balancer serving a default "It works!" page
• An API returning {"error": "service unavailable"} with a 200 status
• A cached/stale response that's technically up but completely wrong
• A login page shown instead of the protected resource

In each case, a naive monitor sees "200 — all good" while your users see something broken.

What Good API Monitoring Checks

1. Reachability — does the endpoint respond at all?
2. Status code — is it the code you expect (not just any 2xx)?
3. Response time — is it fast enough to be usable?
4. The right behavior — does it respond consistently from an outside vantage point?

ismysiteup lets you set the expected status code per monitor, so you're not just checking "did it respond" but "did it respond correctly." A health-check endpoint that should return 200 will alert you the moment it returns anything else.

Monitor the Endpoints That Matter

For an API-backed product, watch:

• Your health-check / status endpoint
• Critical read endpoints (the data your app can't function without)
• Auth endpoints (if login breaks, nothing else matters)
• Webhook receivers (silent failures here are the hardest to notice)

Use short intervals on the endpoints your product depends on most — here's why interval speed is so important.

Catch Slowdowns Before They Become Outages

APIs rarely fail all at once — they degrade. Response times creep up, timeouts start appearing, and then it falls over. Tracking response time turns a future outage into today's warning, giving you room to fix it calmly.

Set Up API Monitoring

Add your endpoints free, set the expected status code, choose a tight interval, and connect an alert channel. Now you'll know the moment your API misbehaves — not just when it disappears entirely.

Related reading: HTTP Status Codes Explained · How ismysiteup Works