📚 Quick Definition

The target resource has been assigned a new permanent URI and any future references should use the new URI. Search engines will update their index to the new URL. This is the most important redirect for SEO and is used when a page's URL changes permanently.

⏱ When It Occurs

A 301 response is returned when a server wants to tell clients and search engines that a resource has permanently moved to a different URL. The server includes a Location header with the new URI. Browsers automatically follow the redirect, and search engines transfer ranking signals to the new URL.

🛠 Common Use Cases

  • HTTP to HTTPS migration (redirecting all HTTP traffic to HTTPS)
  • Domain name change (old-domain.com to new-domain.com)
  • Removing www or adding www (standardizing the URL format)
  • URL structure change (e.g., /blog/post-title to /articles/post-title)
  • Merging duplicate content under a single canonical URL
  • Old permalink to new permalink after a CMS migration

✅ Best Practices

  • Always include a Location header with the new URL in the response
  • Use 301 only for permanent URL changes - use 302 or 307 for temporary changes
  • 301 passes most link equity (SEO juice) to the new URL
  • Be aware that 301 may change POST to GET - use 308 if the method must stay the same
  • Submit the new URL to Google Search Console to speed up re-indexing
  • Update your internal links too - don't rely solely on the redirect

📡 HTTP Example

Request
GET /old-page HTTP/1.1
Host: www.example.com
Response
HTTP/1.1 301 Moved Permanently
Location: https://www.example.com/new-page
Content-Length: 0

❓ Frequently Asked Questions

Does 301 pass SEO value? +
Yes, a 301 redirect passes most of the link equity (also called "link juice" or "SEO value") from the original URL to the new URL. Search engines like Google have confirmed that 301 redirects transfer ranking signals. This makes 301 the preferred redirect type for site migrations, domain changes, and URL restructuring.
What's the difference between 301 and 308? +
Both 301 and 308 are permanent redirects, but they differ in how they handle the HTTP method. A 301 redirect may change a POST request to a GET request when following the redirect. A 308 Permanent Redirect guarantees that the HTTP method and body will not change. Use 308 when you need to preserve POST requests through the redirect.
How long do browsers cache 301s? +
Browsers can cache 301 redirects indefinitely since they are permanent by definition. This means once a browser sees a 301, it may never request the original URL again and will go directly to the new URL. Be very careful with 301 redirects because they are difficult to undo - users would need to clear their browser cache to see any changes.