TECHNICAL SEO
HTTP status codes for SEO: a practical reference
The three-digit code a server returns with each response, which crawlers act on before reading the page.
- Beginner level
- 3 primary sources
- Reviewed 29 October 2026
- TopicTechnical SEOAlso in Crawling, rendering & indexing, SEO auditing & troubleshooting
- LevelBeginnerNo background needed
- Also calledHTTP response codes
- Sources3 primary sourcesGoogle Search Central, IETF and more
- Reviewed29 October 2026Re-checked every 12 months
On this page
Quick definition
An HTTP status code is the three-digit number a server returns with every response to say what happened: 2xx for success, 3xx for redirects, 4xx for client errors such as a missing page, and 5xx for server errors. Search engines read the code before the content and act on it.
The codes that matter for search
| Code | Meaning | What search engines do |
|---|---|---|
| 200 OK | The page was returned | Content can be indexed (unless noindexed) |
| 301 / 308 | Moved permanently | Follow it; strong signal that the target is the canonical |
| 302 / 307 | Found / temporary redirect | Follow it; weaker canonical signal, the source may stay indexed for a while |
| 304 Not Modified | Unchanged since the last crawl | Reuse the stored version |
| 404 Not Found | No page at this URL | Drop the URL from the index over time |
| 410 Gone | Removed on purpose | Treated much like 404 |
| 429 Too Many Requests | Rate limited | Google treats it like a server error and slows crawling |
| 500 / 502 / 503 | Server errors | Crawling slows; URLs that keep failing are eventually dropped |
Why it matters
A wrong status code tells search engines something different from what visitors see. A missing product that returns 200 with "not available" is a soft 404; a live page that returns 500 to bots while working for visitors loses visibility silently; a maintenance page served with 200 can replace your content in the index.
How to check it
- Request important URLs directly and read the status line, not just the page in a browser (browsers follow redirects silently).
- Check that what crawlers receive matches what visitors receive: firewalls and bot protection sometimes answer bots with 403 or 503.
- During planned maintenance, return 503 with a
Retry-Afterheader, and keep it short; extended 5xx responses lead to dropped URLs. - Monitor the share of 4xx and 5xx responses to verified crawlers in logs or Search Console‘s Crawl stats.
Common mistakes and misconceptions
Myth Every 404 is an SEO problem.
In fact 404 is the correct response for a URL that should not exist. It becomes a problem when important pages or pages with valuable links return it.
Myth A 503 protects rankings indefinitely during an outage.
In fact It helps for short outages. If a URL keeps returning server errors for days, Google starts dropping it.
Check it on your site
Free tools, no sign-up
- FreeBulk HTTP Status CheckerCheck up to 25 URLs at once: status code, final URL after redirects, number of redirects and response time.Open the tool
- FreeRedirect Chain CheckerFollow every redirect from a URL, hop by hop, with status codes and timings, and spot chains, temporary redirects and dead ends.Open the tool
- FreeHTTP Header AnalyzerSee every response header a URL sends and check the ones that matter for indexing, security and caching.Open the tool
- FreeExternal Link Status CheckerCheck whether the links on a page to other sites still work, redirect or are broken.Open the tool
In the NdovuSEOLabs platform
Run the same checks on every page of your site, with your own data.
Sources and review
- How HTTP status codes, and network and DNS errors affect Google Search Google Search Central
- RFC 9110: HTTP Semantics IETF
- HTTP response status codes MDN Web Docs
Written and maintained by Ndovu SEO Labs. First published 29 October 2026. Facts last checked against the sources above on 29 October 2026. How we write and review the glossary.