HTTP Status Code

A three-digit number returned by a web server indicating the result of a client's request.

Sep 7, 2026 / About 1 min read

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An HTTP status code is a three-digit number included in every HTTP response that indicates the outcome of the request. Status codes are grouped into five classes: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client error), and 5xx (server error). Each code conveys specific information about what happened when the server processed the request.

For URL shortening services, the 3xx class is most relevant. The 301 (Moved Permanently) and 302 (Found) codes are the workhorses of URL redirection. The 200 (OK) code indicates successful content delivery, while 404 (Not Found) signals that a short code does not exist in the database. Understanding these codes is essential for debugging redirect issues and monitoring service health.

Beyond the common codes, several less-known status codes are relevant to URL shortening. The 410 (Gone) code indicates that a resource has been intentionally removed, which is useful for expired short URLs. The 429 (Too Many Requests) code is used for rate limiting API access. The 503 (Service Unavailable) code signals temporary downtime.

Monitoring HTTP status codes is a key operational practice. Tracking the distribution of response codes over time reveals patterns such as increasing 404 rates (indicating broken links), spikes in 5xx errors (indicating server issues), or unusual redirect patterns.

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Related Terms

301 Redirect

A permanent HTTP redirect that tells browsers and search engines the resource has moved permanently to a new URL.

302 Redirect

A temporary HTTP redirect indicating the resource is temporarily located at a different URL.

404 Not Found

An HTTP status code indicating that the server cannot find the requested resource at the specified URL.

308 Redirect

A permanent HTTP redirect that preserves the original request method, combining the permanence of 301 with the method preservation of 307.

Redirect Loop

An error condition where two or more URLs redirect to each other in a circular pattern, preventing the browser from reaching any destination.

Response Code Negotiation

A design technique that dynamically selects the HTTP status code returned during redirects based on client type and request conditions.

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FAQ

What are the most commonly used HTTP status codes?

200 (OK), 301 (Moved Permanently), 302 (Found), 404 (Not Found), and 500 (Internal Server Error) are representative examples. For URL shortening services, 301 and 302 are particularly important.

Where can you check HTTP status codes?

You can check them using browser developer tools (Network tab), the curl command, or online HTTP header checkers.

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