HTTP Status Codes Explained — Complete SEO Guide

Definition

HTTP status codes are three-digit numbers returned by web servers in response to a client's request. Every time a browser, search engine crawler, or API client requests a URL, the server responds with a status code that indicates whether the request was successful, redirected, or resulted in an error.

Status codes are grouped into five categories based on their first digit: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client error), and 5xx (server error). For SEO and broken link checking, the most important categories are 2xx, 3xx, and 4xx.

Status code categories

• 2xx — Success — the request was received, understood, and processed. 200 OK is the most common: the page loaded successfully.
• 3xx — Redirection — the requested resource has moved. 301 Moved Permanently and 302 Found are the most common. See our guide on 301 redirects.
• 4xx — Client Error — the request was invalid or the resource doesn't exist. 404 Not Found is the most common — see 404 errors explained.
• 5xx — Server Error — the server failed to fulfill a valid request. 500 Internal Server Error and 503 Service Unavailable are the most common.

Status codes that matter for SEO

Not all status codes are equally important for SEO. Here are the ones you should monitor:

• 200 OK — the ideal response for all your live pages. If a page should be accessible, it should return 200.
• 301 Moved Permanently — passes link equity to the new URL. Use for permanent URL changes, domain migrations, and HTTPS upgrades.
• 302 Found — temporary redirect. Use sparingly; search engines may not transfer link equity as effectively as with 301s.
• 404 Not Found — the page doesn't exist. A few 404s are normal; many 404s from internal links indicate a problem. See broken links.
• 410 Gone — explicitly tells search engines the page has been permanently removed. Stronger signal than 404 for content you've intentionally deleted.
• 500 Internal Server Error — indicates a server-side problem. Persistent 500 errors can cause search engines to reduce crawl frequency.
• 503 Service Unavailable — temporary server issue. Tells crawlers to come back later. Useful during planned maintenance.

How to check HTTP status codes

Use our free HTTP Status Checker to check the status code of any URL. For a comprehensive view of all status codes across your entire site, run a full broken link scan — it reports the HTTP status of every link on every page.

Google Search Console also reports status codes in the Coverage report, showing which of your pages return errors or redirects.

Common status code issues

• Redirect chains — multiple redirects in sequence (301 → 301 → 200) slow down page loads and dilute link equity. See redirect chains.
• Soft 404s — pages that return 200 but display error content. See soft 404s explained.
• Mixed content after HTTPS migration — HTTP resources loaded on HTTPS pages may trigger security warnings or be blocked entirely.
• Intermittent 5xx errors — server errors that come and go can be hard to catch without automated monitoring.

Understanding HTTP status codes is fundamental to maintaining a healthy website. Scan your site to see every status code returned by your pages and links.