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HTTP

HTTP 301Moved Permanently

HTTP 301 Moved Permanently tells the client that the resource now lives at the URL in the Location header and that future requests should go there directly. Browsers cache 301s aggressively, and search engines transfer ranking signals to the new URL, which makes it the right code for site migrations and HTTP-to-HTTPS redirects.

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What 301 means

The server is saying: "this resource has moved for good; use the new address from now on." Clients follow the Location header automatically and may update bookmarks or links. Search engines treat the new URL as canonical and move the old URL's indexing signals to it.

Behaviour details

  • Caching. RFC 9110 makes 301 cacheable by default. Chrome and Firefox remember a 301 until their cache is cleared, so a mistaken 301 is hard to retract for existing visitors.
  • Method change. Historically clients converted POST to GET when following a 301, and the spec still permits it. Use 308 semantics (Permanent Redirect) when the method must be preserved.
  • Chains. Each hop costs a round trip and dilutes crawl efficiency. Redirect directly to the final URL.

Common uses

  1. HTTP → HTTPS on port 80 to 443.
  2. www ↔ non-www canonicalisation.
  3. URL restructuring during a redesign.
  4. Domain migration, page by page.
  5. Trailing-slash normalisation.

Configuring

Apache (.htaccess or virtual host):

apache
Redirect 301 /old-page/ /new-page/
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

nginx:

nginx
location = /old-page/ { return 301 /new-page/; }
server { listen 80; return 301 https://$host$request_uri; }

Verifying

cmd
curl -I http://example.com/old-page/

Expect HTTP/1.1 301 Moved Permanently and a Location: line. curl -IL follows the chain and prints every hop, which reveals redirect loops and chains. The 301 vs 302 guide covers choosing between the two.

Frequently asked questions

How do I undo a 301?

Serve a new redirect from the target back, and accept that browsers which cached the old 301 will keep following it until their cache clears. This is why 301s should only be used for changes that are genuinely permanent.

Does a 301 lose ranking?

Google has stated that 301 redirects do not lose PageRank. Signals consolidate to the destination, provided the destination is relevant and the redirect is direct, not a chain.

301 or 308?

Both are permanent. 308 guarantees the method and body are preserved (a POST stays a POST). 301 allows clients to switch to GET. For ordinary page moves 301 is universal; for API endpoints 308 is safer.

Sources

Port records

Port 80 HTTPPort 80 is the default TCP port for HTTP, the unencrypted web protocol. Modern websites…Port 443 HTTPSPort 443 is the standard TCP port for HTTPS, the encrypted form of HTTP. Web browsers connect…

Command records

curl Transfer data and inspect HTTP from the command linecurl transfers data to and from a server and is built into Windows 10 and 11. For diagnostics…

HTTP records

HTTP 302 FoundHTTP 302 Found tells the client that the resource is temporarily at the URL in the Location…HTTP 304 Not ModifiedHTTP 304 Not Modified is the server's answer to a conditional request: the client sent…HTTP vs HTTPS What the S changesHTTPS is HTTP carried inside a TLS session. The requests and responses are identical; TLS adds…HTTP 404 Not FoundHTTP 404 Not Found means the server is reachable but has nothing at the requested URL. The…HTTP 410 GoneHTTP 410 Gone means the resource existed, has been removed on purpose, and will not return. It…HTTP 200 OKHTTP 200 OK means the server received the request, understood it and is returning the result.…

Utilities

URL ParserParse a URL into its scheme, host, port, path, query parameters and fragment, and decode the…

Guides

301 vs 302 redirect Which redirect to use and whyUse a 301 (permanent) redirect when a URL has moved for good: migrations, HTTPS enforcement,…