SEO Reference
HTTP Status Codes for SEO
Status codes are where site migrations succeed or fail. This table is what I hand to engineering during a replatform, because the difference between a 301 and a 302 is the difference between keeping your rankings and rebuilding them.
| Code | Meaning | SEO effect |
|---|---|---|
| 200 | OK | Page is crawled and eligible for indexing |
| 301 | Moved permanently | Signals consolidation to the new URL |
| 302 | Found, temporary redirect | Original URL usually kept as canonical |
| 304 | Not modified | Efficient recrawl, no content returned |
| 307 | Temporary redirect | Method preserving temporary equivalent of 302 |
| 308 | Permanent redirect | Method preserving permanent equivalent of 301 |
| 404 | Not found | Dropped from the index over time |
| 410 | Gone | Signals deliberate removal, often processed faster |
| 429 | Too many requests | Crawl rate is throttled |
| 500 | Internal server error | Crawling slows, prolonged errors risk deindexing |
| 503 | Service unavailable | Correct code for planned maintenance |
| Situation | Correct code |
|---|---|
| Permanent URL change or domain migration | 301 |
| Temporary campaign or seasonal page swap | 302 |
| Permanent change on a POST endpoint | 308 |
| Page deleted permanently with no replacement | 410 |
| Page deleted with a close equivalent | 301 to the equivalent |
| Planned downtime or maintenance window | 503 with Retry-After |
Notes
The most common and most expensive mistake in a migration is redirecting everything to the homepage. Google treats a redirect to an irrelevant page as a soft 404, so the signals do not transfer and you lose the ranking history of every URL. Map one to one wherever a reasonable equivalent exists.
A soft 404 is a page that returns 200 while telling the user nothing is there. It wastes crawl budget and confuses indexing. If the content is gone, return the honest status code. Search Console reports these under Page indexing, and they are worth clearing.
Redirect chains lose value and crawl efficiency. After a migration, update internal links, sitemaps and canonical tags to point at the final destination rather than relying on the redirect layer permanently, and keep chains to one hop.
Google's handling of status codes is documented in Search Central and does get refined, particularly around how quickly signals transfer and how long 404s persist in the index. Check the current crawling and indexing documentation before planning a large migration.
Frequently asked questions
How long should I keep 301 redirects in place?
At least a year, and ideally permanently. Google needs repeated crawls to fully process the move, and old links from other sites keep sending traffic long after that.
Is 410 better than 404 for deleted pages?
Slightly. Both result in removal, but 410 is an explicit statement of permanent removal and is often processed faster. The practical difference is small.
What code should I use during site maintenance?
503 with a Retry-After header. It tells crawlers to come back rather than treating your outage as content removal.
Official sources
Platforms change specifications without notice. Check the primary documentation before a launch that depends on an exact value.
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