16 Jul 2010, Posted by admin in Nohat, 6 Comments

303 Redirects & SEO

303 redirects are never really talked about in the SEO community, and in truth it’s for good reason.

According to w3.org, 303s basically mean “see other”. The redirecting URL shouldn’t be cached and it generally indicates that the content is held elsewhere. Importantly though, it says this:

“Many pre-HTTP/1.1 user agents do not understand the 303 status”.

SEOs generally know to use a 301 for the vast majority of redirects, but if you ever get a web dev or a design team that wants to use a 303, there’s now a good example of why it should be avoided here:







A search for “Wimbledon” in Google currently shows a blank .com also ranking, just as a 302 often would. This implies that a 303 redirect won’t pass on link value to the main site, like a 301 would, and can cause the redirecting URL to also be listed in the SERPs.

For some reason, the Wimbledon.com URL 301 redirects most users to the correct Wimbledon.org domain, but will show search engines a 303. You can switch your user agent to Googlebot and check.

Yahoo and Bing treat 303s the same way:

Yahoo also doesn’t appear to see the .com redirect properly. And neither does Bing:

So, in summary – 303 redirects don’t appear to work properly to search engines. If you want your permanent redirects to be counted by the search engines, avoid them and use 301 redirect instead.