HTTP 303 See Other

HTTP 303 See Other tells the client to retrieve the resource at a different URL using a GET method, regardless of the original request method. This is the correct redirect to use after a POST (form submission, API call) when you want to redirect to a result page — the classic Post/Redirect/Get (PRG) pattern that prevents duplicate form submissions when users hit refresh.

Debug HTTP 303 live
Analyze real 303 behavior — headers, caching, CORS, redirects
Open Inspector →

Try it (live endpoint)

Response includes the status code, standard headers (including Content-Type), and a small diagnostic JSON body describing the request and returned status.

Simulator URL (copy in the app after load — not a normal link):

https://httpstatus.com/api/status/303

Example request:

curl -i "https://httpstatus.com/api/status/303"
Try in playground

Meaning

The response to the request can be found under another URI using a GET method.

What it guarantees
  • A different URI is involved to complete the intent.
What it does NOT guarantee
  • All clients will automatically follow the redirect.
  • The redirect target is safe to cache unless headers allow it.

When to use this status

  • A resource is available at a different URI and the client should follow it.
  • Canonicalizing paths (slash, www/non-www, http→https).
  • Moving content between endpoints and updating bookmarks.

When NOT to use this status (common misuses)

Redirecting without a stable Location target.
Clients fail to follow; crawlers lose canonical signals.
Using 301/302 for non-GET methods without understanding method rewriting.
Clients can drop bodies or change methods, causing data loss and client bugs.
Redirect loops or long chains.
Crawlers waste crawl budget; clients hang; retries amplify load.

Critical headers that matter

Location
Tells clients where to go next.
Redirects fail or loop; crawlers lose canonical target.
Cache-Control
Controls whether redirects are cached.
Temporary redirects become sticky; permanent redirects never stick.
Vary
Prevents caches mixing redirect variants.
CDNs serve the wrong redirect for different hosts/headers.

Tool interpretation

Browsers
Follows Location for navigations; redirect caching can make behavior sticky. Redirect code choice affects method/body handling.
API clients
May not auto-follow; strict clients require explicit redirect handling. Incorrect redirect semantics can drop bodies or change methods.
Crawlers / SEO tools
Uses redirects for canonicalization; long chains/loops waste crawl budget and dilute signals.
Uptime monitors
Typically marks success; advanced checks may flag header anomalies or latency.
CDNs / reverse proxies
Can cache redirects; Location/Vary/Cache-Control correctness drives global consistency.

Inspector preview (read-only)

On this code, Inspector focuses on semantics, headers, and correctness warnings that commonly affect clients and caches.

Signals it will highlight
  • Status semantics vs method and body expectations
  • Header sanity (Content-Type, Cache-Control, Vary) and evidence completeness
  • Redirect chain length, loops, Location presence, protocol safety
Correctness warnings
No common correctness warnings are specific to this code.

Guided Lab outcome

  • Reproduce HTTP 303 See Other using a controlled endpoint and capture the full exchange.
  • Practice distinguishing status semantics from transport issues (redirects, caching, proxies).
  • Validate redirect correctness (Location, hop count, protocol safety) and SEO impact.

Technical deep dive

303 See Other (RFC 7231 Section 6.4.4) was introduced specifically to address the ambiguity of 301/302 with POST requests. Unlike 301/302 (where method change is a browser bug) and 307 (which preserves the method), 303 explicitly requires changing to GET. This makes it perfect for the PRG pattern: POST /orders → 303 → GET /orders/42/confirmation. The redirect target should be a representation of the action's result, not the action itself. 303 responses are NOT cacheable. For API responses, 303 can redirect from a creation endpoint to the new resource's URL.

Real-world examples

Common 303 See Other scenario 1
When a server returns 303 See Other, it signals specific behavior that clients and intermediaries must handle correctly. For example, in web applications, this status is commonly encountered during URL routing, content negotiation, or resource management operations.
CDN and proxy behavior with 303
CDNs and reverse proxies handle 303 See Other according to their configuration. The caching and forwarding behavior depends on whether the status is cacheable by default (per RFC 7231) and the presence of Cache-Control headers. Misconfigured intermediaries can cause redirect loops or cache stale redirects.
API design with 303 See Other
In RESTful API design, 303 See Other serves a specific semantic purpose. API gateways may intercept and modify these responses for versioning, rate limiting, or traffic management. Understanding when to use 303 versus similar status codes is critical for correct client behavior.

Framework behavior

Express.js (Node)
Express: res.redirect(303, 'https://new-url.com'). For 301/308 permanent: ensure the Location header is correct as browsers may cache it permanently.
Django / DRF (Python)
Django: return HttpResponseRedirect('/new-url/', status=303) or use the shortcut redirect() with permanent parameter for 301/308.
Spring Boot (Java)
Spring: return ResponseEntity.status(303).header("Location", "/new-url").build(). Spring's RedirectView can be configured with specific status codes.
FastAPI (Python)
FastAPI: return RedirectResponse(url='/new-url', status_code=303). For API redirects, ensure the client follows redirects with method preservation when using 307/308.

Debugging guide

  1. Check the Location header value — typos or relative URLs in Location can cause redirect loops or 404s
  2. Verify caching behavior: NOT cacheable by default — check Cache-Control headers
  3. Test with curl -v -L to follow redirects and see the full chain
  4. Check for redirect chains — each hop adds latency; aim for direct redirects
  5. Monitor for method preservation — 303 must keep the original method

Code snippets

Node.js
app.get('/old-path', (req, res) => {
  res.redirect(303, '/new-path');
});
Python
from fastapi.responses import RedirectResponse

@app.get('/old-path')
async def old_path():
    return RedirectResponse('/new-path', status_code=303)
Java (Spring)
@GetMapping("/old-path")
public ResponseEntity<Void> oldPath() {
    return ResponseEntity.status(303)
        .header("Location", "/new-path")
        .build();
}
Go
func oldPathHandler(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/new-path", 303)
}

FAQ

When should I use 303 See Other vs other redirect codes?
303 See Other is temporary and explicitly changes to GET. Choose based on permanence (will the redirect stay?) and method preservation (does POST need to stay POST?).
How do search engines handle 303 See Other?
Search engines treat this as temporary and continue indexing the original URL. They do not transfer PageRank.
Is 303 See Other cacheable?
No, 303 is NOT cacheable by default. Add Cache-Control: max-age=N if you want intermediaries to cache it.
What are common pitfalls with 303 See Other?
Common issues include: redirect loops (A→B→A), missing Location header, relative vs absolute URLs in Location, browser compatibility issues, and excessive redirect chains that add latency.

Client expectation contract

Client can assume
  • A different URI is involved; Location may be required.
Client must NOT assume
  • Redirects will be followed automatically by all clients.
Retry behavior
Retries are generally unnecessary; treat as final unless domain rules require revalidation.
Monitoring classification
Redirect (policy-dependent)
Validate Location, caching headers, and chain behavior. Redirect loops/chains should alert.

Related status codes

302 Found
The URL of the requested resource has been changed temporarily.
304 Not Modified
Indicates that the resource has not been modified since the version specified by the request headers (If-None-Match or If-Modified-Since). The client should use its cached copy.

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