How do HTTP Status Codes Affect SEO?

These status codes are purely informational and have no real-world implications on a website’s SEO.

Common examples: 

• 100 (Continue) – this designates the initial request was received and not yet rejected by the server.
• 101 (Switching Protocols) – the originating server understands and can fulfil the client request via the Upgrade header field.
• 102 (Processing) – this response code essentially informs the client that the request to the server was accepted, although the server hasn’t yet completed the request.

2xx status codes tell you that a browser’s request to the server was successful. Visitors would never usually see a 2xx status code because a page loads perfectly fine, and no action needs to be taken.

If a page has a 200 (OK) status code, you don’t really need to do anything. The only exception is if you were running a site through a tool like Semrush or Screaming Frog for a content audit.

Common examples:

• 201 (Created) – this code tells you the server request was satisfied and that one or more resources were created.
• 202 (Accepted) – this means the server request was accepted for processing, but the processing hasn’t been completed yet.
• 203 (Non-Authoritative Information) – this code indicates that a transforming proxy has modified a payload from the origin server’s 200 (OK) response. 
• 204 (No Content) – once the payload request has been fulfilled, no more content can be sent in the response payload body.
• 205 (Reset Content) – similarly to the 204 status code, with the exception being that responses require the client to reset the document view.
• 206 (Partial Content) – the transfers of one or more page components (which correspond to satisfiable ranges found in the range header field of the request), i.e. the server fulfilling the range request for the target resource.
• 207 (Multi-Status) – displaying information regarding more than one resource, in situations where more than one http status code may be required.

Mainly, 3xx codes indicate redirects, usually temporary or permanent. These redirects are necessary for preserving the SEO of a website. 

These codes help explain to Google whether a page redirect is permanent or temporary, or that different issues exist, such as whether pages of content are no longer needed. 

Common examples:

• 300 (Multiple Choices) – this redirect involves multiple documents with more than one version, each with a unique identification. Information is provided in a way where the user can select which version they want.
• 301 (Moved Permanently) – these are permanent redirects. For any site migrations where you have to transfer SEO value from one URL to another on a permanent basis, these codes are necessary. The requested resource has been assigned a new permanent URI (Uniform Resource Identifier), and the server should be redirecting you there.
• 302 (Found) – otherwise known as temporary redirects, rather than permanent 301s. These are similar to 301 redirects but are temporary, and you may find 302s instead of 301s on sites where permanent redirects haven’t been properly implemented.
• 303 (See Other) – the URL redirects the user agent to a different resource. The intention behind this 3xx redirect is to provide an indirect response to the initial request.
• 304 (Not Modified) – this code indicates that there is no need to resubmit the resources; in other words, an implicit redirection to a resourced that’s cached.
• 305 (Use Proxy) – this is now deprecated and does not have any SEO impact. 
• 307 (Temporary Redirect) – this temporary redirect code explains the target page is temporarily residing on a different URL. This tells the user agent that it shouldn’t make any changes to the request method if an auto-redirect is applied to that URL. 
• 308 (Permanent Redirect) – very similar to a 301 redirect.

4xx client error status codes indicate that something isn’t loading and explain why that’s happening. While each 4xx code indicates a unique problem, the result is usually the same, and it’s an error from the client’s side. 

Any 4xx errors should ideally be assessed in the preliminary stages of any technical website audit, and any errors should be fixed as soon as they’re spotted. 

The most common types of 4xx status codes are 400 (bad request), 403 (forbidden) and 404 (not found), which essentially indicate a resource is unavailable and unable to load. The Screaming Frog Spider tool, for example, will crawl a site and report a 404 status if a link on a page points to somewhere that doesn’t exist.

Tools like Screaming Frog won’t immediately fix these broken links, but the SEO Spider will highlight which ones are broken. This allows SEO experts like us, to decide the best way to proceed with each broken link. 

Common examples:

• 401 (Unauthorised) – for a request to be processed, user authentication is required. A 401 status error indicates the header in your request didn’t contain the authorisation codes necessary to view the page content.
• 403 (Forbidden) – the request was received, but the server is not processing it. Even with authorisation, this request would be unsuccessful.
• 404 (Not Found) – this means that the server cannot find anything that matched the requested URI, regardless of temporary or permanent status. You’ll often encounter 404 errors when a server doesn’t unveil specifically why a request was refused or if there is no other applicable response.