How do I undo a 301 that browsers have cached?
You cannot clear other people's caches remotely. Redirect the new URL back, or serve the old URL directly with a cache-busting response, and wait. Browsers may hold a cached 301 for a long time.
HTTP 301 MOVED PERMANENTLY
The resource has a new permanent URL. Search engines move ranking to it. Clients may change POST to GET. 301 belongs to the 3xx redirection class and is defined in RFC 9110.
Loading the workbench.
About HTTP 301
What Does HTTP 301 Moved Permanently Mean?
The resource has a new permanent URL. Search engines move ranking to it. Clients may change POST to GET. The code is registered with IANA and defined in RFC 9110.
Redirection: the client must take another step to finish the request. Every code from 300 to 399 shares that general meaning, so a client that does not recognise 301 must treat it like 300.
When Do You See a 301 Response?
301 Moved Permanently says the resource has a new URL for good. It is the classic redirect for domain changes, HTTP to HTTPS moves, removing or adding www, and restructured paths. Search engines transfer ranking signals to the target and update their index. Browsers cache 301s aggressively, often with no expiry, which makes a mistaken 301 hard to undo. For historical reasons, clients may turn a POST into a GET when following it.
How Do You Handle a 301?
Servers must send a Location header with the new URL, preferably absolute. Redirect straight to the final destination in one hop rather than chaining http to https to www to path. If the request method must be preserved, for example an API receiving POSTs, use 308 instead. Test new rules with a 302 first, because users who already cached a wrong 301 will keep following it until they clear their cache.
What Does a 301 Response Look Like?
HTTP/1.1 301 Moved Permanently
Location: https://www.example.com/new-path
Content-Length: 0301 is cacheable by default under RFC 9110: a browser or CDN may store it and reuse it even without explicit freshness headers, using a heuristic lifetime. Send Cache-Control to say exactly how long.
To inspect a real one without sending it anywhere:
- Copy the response headers from your browser Network tab, or from
curl -i. - Paste them into the Header decoder to see every header explained.
- Check caching in the Cache lane and the Location target in the decoder.
Which Status Codes Are Related to 301?
- 308 Permanent Redirect: A permanent redirect that keeps the method and body.
- 302 Found: A temporary redirect. Clients may change POST to GET; use 307 to forbid that.
- 307 Temporary Redirect: A temporary redirect that keeps the method and body: a POST stays a POST.
- 410 Gone: Removed on purpose and not coming back. Search engines drop it faster than a 404.
Browse every code on the HTTP status codes page.
What Other Lanes Are in the Reference Section?
- HTTP status codes: Every IANA-registered status code, with a page per code.
- MIME types: File extensions to Content-Type, searchable both ways, plus a Content-Type parser.
- HTTP methods: GET, POST, PUT, PATCH, DELETE and the rest: safe, idempotent, cacheable.
Elsewhere in 2http: Header decoder, Cookie decoder, Cache-Control decoder, CORS checker, User-agent parser, and all eleven lanes on the 2http home page. Part of the 2suite.io privacy-first ecosystem.
Frequently Asked Questions
Should I use 301 or 308 for permanent redirects?
Use 301 for normal page moves, which are GET requests. Use 308 when the method and body must be kept, such as API endpoints that receive POST or PUT.
Is HTTP 301 an error?
No. 301 is a redirection response, not an error.
Is a 301 response cacheable by default?
Yes. RFC 9110 lists 301 as heuristically cacheable, so caches may store it without explicit headers. Use Cache-Control to control how long.
How Can You Verify That Nothing Leaves This Browser?
You do not have to take our word that your headers stay here. Developer tools show every request a page makes, so you can watch this page work and confirm that nothing is sent. The check takes under a minute.
- Open your browser developer tools with
F12, orCmd+Option+Ion a Mac, and select the Network tab. - Reload the page and let it finish. You will see the page's own files, its web fonts, and one anonymous page-view request. Nothing has been typed yet, so none of them can contain your headers.
- Click the clear icon in the Network tab so that the log is empty.
- Paste real headers into any lane and read the result.
- Look at the Network tab again. It is still empty. For extra proof, turn on offline mode after the page loads and every lane keeps working.
Only two things can add a line to that log, and neither carries your headers. Submitting the feedback form sends the vote and comment you typed. Typing characters in a script the page has not displayed yet, such as Cyrillic or Greek, can make the browser fetch the matching font file, and that request names only the font.
2http never sends a request on your behalf: the request builder writes code for you to run, and the meta inspector reads source you paste instead of fetching a URL. The production site also sends a Content-Security-Policy header that tells your browser to refuse connections to anywhere except this site and the anonymous analytics endpoint.