301 Moved Permanently

The resource has permanently moved to a new URL. Browsers and search engines should update their references to use the new location.

What It Means

The server is telling clients that this URL is permanently retired. Future requests should go directly to the URL specified in the Location header. Browsers cache 301 responses aggressively, often indefinitely. Search engines transfer link equity (ranking signals) to the new URL.

When to Use 301

• Domain migrations. Moving from old-domain.com to new-domain.com.
• HTTP to HTTPS redirect. Forcing all traffic to the secure version.
• URL structure changes. Old path format to new path format.
• Trailing slash normalization. Canonicalizing /page vs /page/.

Do NOT use 301 for temporary changes. Use 302 (Found) or 307 (Temporary Redirect) instead.

Common Issues

• Redirect loops. A redirects to B, B redirects back to A. The browser gives up after a few cycles.
• Redirect chains. Three or more hops (A to B to C to D). Each hop adds latency and some crawlers stop following after a few redirects.
• Browser caching a wrong 301. Because browsers cache 301s indefinitely, a mistaken 301 is very hard to undo. Users must manually clear their browser cache.
• 301 vs 308. A 301 may change the HTTP method from POST to GET. If you need to preserve the original method, use 308 (Permanent Redirect) instead.

How to Diagnose

Use the Probe tool to see the full redirect chain. Check the Location header value at each hop. Verify that the final destination returns a 200 and serves the expected content.