HTTP status codes

HTTP status codes — the SEO reference

HTTP status codes are three-digit server responses (like 200, 404 or 301) that tell browsers and crawlers the result of a request. Getting them right is fundamental to how a site is crawled, indexed and ranked.

An HTTP status code is the three-digit number a server returns with every request, telling the browser — and search engine crawlers — what happened. For SEO they matter because they decide whether a page can be crawled, indexed and ranked, and how link signals move when URLs change.

2xx — Success

200 OKHTTP 200 means the request succeeded and the page returned normally.

3xx — Redirection

304 Not ModifiedHTTP 304 tells the client the page hasn't changed since it was last cached.

4xx — Client errors

400 Bad RequestHTTP 400 means the server couldn't process the request due to a client-side error. 401 UnauthorizedHTTP 401 means authentication is required and has not been provided. 403 ForbiddenHTTP 403 means the server understood the request but refuses to authorise it. 404 Not FoundHTTP 404 means the requested page could not be found on the server. 405 Method Not AllowedHTTP 405 means the HTTP method used isn't allowed for that resource. 408 Request TimeoutHTTP 408 means the server timed out waiting for the client's request.

5xx — Server errors

500 Internal Server ErrorHTTP 500 is a generic server-side error meaning something went wrong on the server. 502 Bad GatewayHTTP 502 means a server acting as a gateway got an invalid response upstream. 503 Service UnavailableHTTP 503 means the server is temporarily unable to handle the request.
This is a technical SEO topic I handle for clients: Technical SEO →

Related terms

CrawlerA bot that discovers and reads pages so they can be indexed. 301 redirectA permanent redirect that moves a URL and passes its ranking signals.

Related services

Technical SEOCrawl, rendering, Core Web Vitals and clean indexation. SEO AuditDiagnose what's holding the site back, prioritised.

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