What Are HTTP Status Codes?
HTTP status codes are three-digit numbers returned by web servers to indicate the outcome of a request. They help you understand whether your website is working correctly or if there are issues that need attention.
Status Code Categories
2xx - Success (Green)
These codes indicate the request was successful.
| Code | Meaning | What It Means For You |
|---|---|---|
| 200 | OK | Everything is working perfectly. Your website responded correctly. |
| 201 | Created | A resource was successfully created (common in API responses). |
| 204 | No Content | Request succeeded but there is no content to return. |
3xx - Redirection (Blue)
These codes indicate the resource has moved.
| Code | Meaning | What It Means For You |
|---|---|---|
| 301 | Moved Permanently | The page has permanently moved to a new URL. Update your monitor URL. |
| 302 | Found | Temporary redirect to another URL. Usually not a concern. |
| 304 | Not Modified | The cached version is still valid. This is normal behavior. |
| 307 | Temporary Redirect | Similar to 302, the resource is temporarily at another location. |
| 308 | Permanent Redirect | Similar to 301, but the request method should not change. |
4xx - Client Errors (Yellow/Orange)
These codes indicate there is a problem with the request.
| Code | Meaning | What It Means For You |
|---|---|---|
| 400 | Bad Request | The server could not understand the request. Check your URL. |
| 401 | Unauthorized | Authentication is required. You may need to add credentials. |
| 403 | Forbidden | Access is denied. The server understood but refuses the request. |
| 404 | Not Found | The page does not exist. Check if the URL is correct. |
| 405 | Method Not Allowed | The HTTP method (GET, POST, etc.) is not supported. |
| 408 | Request Timeout | The server timed out waiting for the request. |
| 429 | Too Many Requests | You have been rate limited. Reduce check frequency. |
| 451 | Unavailable For Legal Reasons | Content blocked due to legal requirements. |
5xx - Server Errors (Red)
These codes indicate a problem on the server side.
| Code | Meaning | What It Means For You |
|---|---|---|
| 500 | Internal Server Error | Something went wrong on the server. Contact the site administrator. |
| 502 | Bad Gateway | The server received an invalid response from an upstream server. |
| 503 | Service Unavailable | The server is temporarily overloaded or down for maintenance. |
| 504 | Gateway Timeout | The upstream server did not respond in time. |
Cloudflare-Specific Codes (5xx)
If your site uses Cloudflare, you may see these additional codes:
| Code | Meaning | What It Means For You |
|---|---|---|
| 520 | Unknown Error | Cloudflare received an unexpected response from your origin server. |
| 521 | Web Server Down | Your origin server refused the connection from Cloudflare. |
| 522 | Connection Timed Out | Cloudflare could not establish a TCP connection to your origin. |
| 523 | Origin Unreachable | Cloudflare could not reach your origin server (DNS issue). |
| 524 | Timeout Occurred | Cloudflare connected but your origin did not respond in time. |
| 525 | SSL Handshake Failed | SSL/TLS handshake between Cloudflare and origin failed. |
| 526 | Invalid SSL Certificate | Your origin server has an invalid or expired SSL certificate. |
What To Do When You See These Codes
- 2xx codes: No action needed - your site is working correctly.
- 3xx codes: Usually fine, but consider updating your monitor URL to the final destination.
- 4xx codes: Check your URL, credentials, or contact the site owner.
- 5xx codes: Contact your hosting provider or check your server logs.
Tips
- Hover over any status code badge to see a quick description
- Use the check history to identify patterns in status code changes
- Set up alerts to be notified when status codes change unexpectedly