303 See Other
The server redirects the client to get the requested resource at another URI with a GET request.
Usually happens because:
- ☑ Post-Redirect-Get patterns preventing form double-submissions.
- ☑ File upload managers sending clients
🔍 Quick Checklist:
Meaning
The HTTP 303 See Other redirection status code indicates that the redirects do not link to the requested resource itself, but to another page (such as a confirmation page or upload progress bar). This status code is commonly returned after a POST form submission.
Root Causes
- Post-Redirect-Get patterns preventing form double-submissions.
- File upload managers sending clients to progress monitor pages.
| Cause | Frequency |
|---|---|
| Post-Redirect-Get patterns preventing form double-submissions. | ⭐⭐⭐⭐⭐ |
| File upload managers sending clients | ⭐⭐⭐⭐ |
Common Mistakes
- Using 302 instead of 303 inside REST APIs (which might cause clients to re-issue POST requests to the redirection endpoint).
- Omitting the Location header in the 303 response.
How to Fix
Framework-Specific Examples
Redirecting form submissions using 303 status in Express.
app.post('/register', (req, res) => {
// save user...
res.redirect(303, '/welcome');
});Server Configuration Examples
Forcing upstream redirects to return 303 status.
# Nginx forwards 303 status transparentlyPrevention
- Enforce Post-Redirect-Get (PRG) patterns for all state-changing operations.
- Check API specs checking redirect response method conversions.
Frequently Asked Questions (FAQ)
Q: What is the Post-Redirect-Get (PRG) pattern?
PRG is a web development design pattern that prevents duplicate form submissions. Instead of returning a success page directly in the POST response, the server redirects the client to a GET success page.
Q: Is HTTP 303 cached?
No. A 303 response is never cached, as it always refers to the temporary result of a stateful request transaction.
Q: Does the client browser change the request method to GET during 303?
Yes. The HTTP specification explicitly states that a client must follow a 303 redirect using a GET request, regardless of the original request method.
Q: When should I use 303 instead of 307?
Use 303 when you *want* the client to switch to GET. Use 307 when the client must reuse the original method (e.g. resending a POST payload).