A 301 is the "this URL has moved forever" redirect. Use it whenever a page genuinely moved permanently — Google transfers the old URL's ranking to the new one, but only if the redirect target is a true equivalent. Don't use 301 for A/B tests, login flows, or…
HTTP 301 Moved Permanently tells browsers, crawlers, and intermediary caches that a URL has permanently changed location. Search engines treat 301 as the strongest signal that the old URL's ranking history, link equity, and indexing status should transfer to the new URL. Browsers cache 301s aggressively (sometimes forever) so once a 301 is set, it sticks — making accidental 301s genuinely painful to reverse. Use 301 whenever a move is permanent: domain change, HTTPS upgrade, slug rewrite, content consolidation. Use 302 (or 307) for anything temporary.
The most SEO-critical of all redirect codes. Google passes ~100% of ranking signals through 301s (since 2016). Done well, a 301 preserves rankings during a migration. Done poorly — redirect chains, blanket redirects to the homepage, broken target URLs — it can erase 40–80% of organic traffic. The "Change of Address" tool in Google Search Console accelerates the transfer for full-domain moves. Browsers cache 301s aggressively, so testing a redirect once it's deployed requires an incognito window or a different browser.
LemWatch detects redirect chains (A→B→C→D) and alerts when chains exceed 2 hops — each hop adds latency and drops ranking signal. We also flag broken final targets (a 301 pointing to a 404 is the worst-case failure mode).
HTTP 301 was defined in the original HTTP/1.0 spec (RFC 1945, 1996) and has stayed unchanged through HTTP/1.1, HTTP/2, and HTTP/3. Its SEO weight comes from a longstanding Google policy: a 301 redirect passes essentially all PageRank to the target. In 2016, Google's Gary Illyes confirmed that 30x redirects no longer lose any PageRank — clearing up a decade-old rumour that 301s leaked ~15% of link equity.
HTTP 301 Moved Permanently tells browsers and search engines that a URL has permanently moved to a new location. All future requests should use the new URL, and search engines should transfer the old URL's ranking signals to the new one.
Whenever a URL has moved or been replaced permanently: HTTP→HTTPS migration, domain change, URL restructure, consolidating duplicate pages, removing trailing slashes consistently. For anything temporary, use 302 or 307 instead.
Yes — essentially 100% of PageRank since Google's 2016 policy update. The old rumour that 301s lose 15% of link equity is no longer true. A clean per-URL 301 preserves ranking; redirect chains and blanket redirects to the homepage do not.
301 is permanent, 302 is temporary. Google treats them differently: 301 transfers ranking signals to the new URL; 302 keeps signals on the original URL because it expects the original to come back. Using 302 when you mean 301 wastes ranking equity until Google reclassifies it.
Forever. Backlinks to the old URL never expire — removing the 301 years later breaks those backlinks and loses the equity they carried. Treat 301s as permanent infrastructure, not temporary fixes.
A redirect chain is multiple consecutive redirects: A→B→C→D. Each hop adds latency, drops a small amount of crawl efficiency, and increases the chance Google gives up before reaching the final URL. Always flatten chains so every old URL points directly at the final destination.
Apache: Redirect 301 /old-url /new-url in your .htaccess file. For pattern-based redirects: RewriteRule ^old-pattern/(.+)$ /new-pattern/$1 [R=301,L]. Always test with curl -I before deploying to production.
Done well: rankings transfer with minimal impact. Done badly (chains, broken targets, mass redirects to homepage): rankings drop sharply. The single biggest factor is per-URL mapping accuracy — each old URL should redirect to its true equivalent, not a generic landing page.