HTTP 301 vs. 302 Redirects – Definition and Differences
Compare permanent and temporary redirects: caching behaviour, method preservation, search implications, and when 307 or 308 is the right choice.
Both send a client elsewhere. The difference is whether the move is permanent, which changes caching, search behaviour, and how hard the decision is to reverse.
1. The Core Difference
| 301 Moved Permanently | 302 Found | |
|---|---|---|
| Meaning | The resource has moved for good | It is temporarily elsewhere |
| Caching | Cached aggressively, often indefinitely | Not cached by default |
| Search engines | Index the target, transfer signals | Keep the original indexed |
| Reversibility | Difficult — caches persist | Easy |
| Bookmarks | Clients may update them | Left unchanged |
2. Why 301 Is Hard to Undo
Browsers cache permanent redirects persistently, sometimes without a stated expiry. A visitor who followed a wrong 301 may keep being redirected long after the server stops sending it, with no way to fix it except clearing their cache.
That is the practical reason to prefer 302 while a change is being tested, and to promote it to 301 only once the destination is settled.
3. The Method Problem
Historically, clients converted POST to GET when following 301 and 302, contrary to the specification. Enough implementations did this that the behaviour became relied upon.
That ambiguity is why two additional codes exist:
- 307 Temporary Redirect — like 302, but the method and body must be preserved.
- 308 Permanent Redirect — like 301, with the same guarantee.
For anything other than a GET, 307 and 308 are the correct choices because they are unambiguous.
4. Choosing
- Content permanently moved to a new URL? 301.
- Temporary move — maintenance, A/B test, seasonal page? 302.
- Redirecting a POST and the method must survive? 307 or 308.
- Unsure whether it is permanent? 302 until you are sure.
5. Search Implications
A permanent redirect tells search engines to index the target and transfer ranking signals from the original. A temporary one tells them to keep the original indexed.
Using 302 for a genuine permanent move leaves the old URL indexed and signals split. Using 301 for a temporary one hands away the original's standing, which is difficult to retrieve.
6. Chains and Loops
Each redirect costs a round trip, and clients stop after a limited number of hops. Chains should be collapsed so the first response points at the final destination.
Two rules disagreeing about a canonical form — trailing slash, protocol, host — produce loops, which surface to users as an error after roughly twenty hops.
7. For Automated Clients
Most HTTP libraries follow redirects automatically, which can obscure what happened. Log the chain and the final URL: a request that succeeded at an unexpected destination is a silent failure worth catching, particularly when a site redirects unrecognised paths to its homepage with a 200.
8. Summary
301 is permanent, cached durably, and transfers search signals; 302 is temporary and reversible. For non-GET requests, 308 and 307 are the unambiguous equivalents.
Default to 302 while a change is provisional, promote to 301 when it is settled, collapse chains, and always record the final URL in automated clients.