Tool review: September 10, 2026.
Enter a three-digit HTTP status code to see its class and a concise interpretation. Status codes are one of the fastest signals for endpoint monitoring, but they describe the HTTP response outcome—not whether the returned content is correct for the user.
Status-code classes
| Range | Class | Monitoring interpretation |
|---|---|---|
| 1xx | Informational | Intermediate protocol response. |
| 2xx | Successful | The request was handled successfully at the HTTP layer. |
| 3xx | Redirection | The client must follow another location or use cached state. |
| 4xx | Client error | The request is invalid, unauthorized, missing or otherwise rejected. |
| 5xx | Server error | The server failed to fulfill an otherwise valid request. |
Why a 200 response can still be wrong
An application can return a generic error page with HTTP 200. For important checks, validate expected text, JSON schema or a complete transaction rather than relying on status alone.
Redirects need deliberate monitoring
A 301 or 302 may be expected, but a new redirect can also add latency or send users to the wrong host. Record the final destination and redirect chain when correctness matters.
Use status with timing and context
For production monitoring, keep the status code beside DNS, connection and response timing plus the check location. A 5xx spike with normal network timing points toward a different investigation than a timeout with no HTTP response at all.
Related resources
Primary reference
Status code is only one layer of health
An HTTP 200 response can still contain an application error, while some redirects or authentication responses may be expected for a particular route. Production checks should combine the expected status with content, header or transaction assertions that reflect what a real caller considers successful.