Every time a browser, crawler or monitoring tool requests a URL, the server returns an HTTP response status code. That small number tells the client whether the request succeeded, was redirected, failed because of the request, or failed because of the server.
For SEO and website maintenance, you do not need to memorize every code. You do need to understand the few that affect crawling, indexing, redirects and user experience.
The five HTTP status code families
- 1xx: informational responses
- 2xx: successful responses
- 3xx: redirection responses
- 4xx: client-side request errors
- 5xx: server-side errors
200 OK: the normal response for a working page
A 200 OK response means the request succeeded. For a normal public webpage that should be available to users and search engines, this is usually the expected status.
A 200 response does not mean that the page is automatically good for SEO. It only tells you that the server successfully returned a response. Content quality, canonicalization, indexing directives and internal linking still matter.
301 and 308: permanent redirects
Use a permanent redirect when a resource has moved to a new URL and you do not expect to restore the old location. The main HTTP choices are 301 Moved Permanently and 308 Permanent Redirect.
Google treats permanent redirects as a signal that the destination should become canonical. For website migrations, changed slugs and consolidated pages, this is usually the right family of redirects.
Avoid long redirect chains. Send the old URL directly to the final relevant destination whenever possible.
302 and 307: temporary redirects
A 302 Found or 307 Temporary Redirect is appropriate when the move is temporary. Google can follow the redirect without treating it as the same permanent canonicalization signal used for a permanent redirect.
The practical rule is simple: if the original URL is expected to return, use a temporary redirect. If the move is permanent, use a permanent redirect.
404 Not Found and 410 Gone
A 404 means the server cannot find the requested resource. A 410 Gone more explicitly states that the resource has been removed and is not expected to return.
Neither code is automatically a problem. If a page has genuinely been removed and there is no relevant replacement, Google recommends returning 404 or 410 rather than redirecting every missing URL to an unrelated page.
If a replacement page exists and genuinely serves the same purpose, a permanent redirect may be more useful to visitors.
429 Too Many Requests
A 429 response usually indicates rate limiting. The client has made too many requests within a given period. On a website, repeated 429 responses can point to aggressive bot traffic, API limits, security rules or server protection settings.
500, 502 and 503: server problems
500 Internal Server Error is a generic server failure. 502 Bad Gateway means a gateway or proxy received an invalid response from an upstream server. 503 Service Unavailable indicates that the server is temporarily unable to handle the request, commonly because of maintenance or overload.
Persistent 5xx errors are important because users and crawlers cannot reliably access the content. A temporary 503 can be appropriate during planned maintenance, especially when paired with a useful error page and a Retry-After header where practical.
A simple SEO audit workflow
- Crawl the site and group URLs by response code.
- Confirm that indexable pages return 200 unless there is a deliberate reason otherwise.
- Review every permanent and temporary redirect.
- Fix internal links that point to redirects, 404s or 5xx errors.
- For removed pages, decide between a relevant permanent redirect and a genuine 404 or 410.
- Investigate recurring 5xx and 429 responses at server, CDN or application level.
Source and further reading
MDN: HTTP response status codes