When you see this status
- Form submission redirects to a results page
- POST request triggers a resource creation, then redirects to the new resource
- API endpoint returns a URI for the client to fetch the result
Common causes
- Client sends POST request, server responds with 303 and new URI
- Server enforces GET after non-idempotent operations
- API follows REST conventions for resource creation
How to debug it
- Verify the Location header contains a valid URI
- Check if the client follows the redirect automatically
- Ensure the response body is empty or minimal
Return this code in your framework
Express (Node.js)
res.status(303).set('Location', '/results/123').send();
FastAPI (Python)
return RedirectResponse('/results/123', status_code=303)
NestJS
@Get() async redirect(): Promise<void> { throw new HttpException('', HttpStatus.SEE_OTHER, { cause: new Error(), description: '/results/123' }); }
Go (net/http)
w.WriteHeader(http.StatusSeeOther); w.Header().Set("Location", "/results/123")
About HTTP 303
HTTP status code 303 See Other is part of the
3xx Redirection family. The resource is temporarily located at another URI, which should be fetched via GET. Understanding it is essential for
backend engineers, API designers, and anyone debugging integrations between services.
The Qaynaq Labs HTTP Status Code Explainer covers all standard codes with practical guidance:
what triggers them, how to debug them in production, and exactly how to return them from common
frameworks. Each code page is hand-curated and verified.