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HTTP/3xx (Redirection)

303 See Other

Directs the client to fetch the resource at another URI using a GET request.

❓ Why does this happen?

The Post/Redirect/Get pattern: after a successful POST form submission, the server redirects to a result page.

✅ How to fix it

Use 303 after POST to prevent duplicate form resubmissions on browser refresh.

Return or handle 303 in your stack

// app/old-path/route.ts
export function GET(request: Request) {
  return Response.redirect(new URL("/new-path", request.url), 303);
}

Live 303 mock endpoint

Point your app, tests, or retry logic at this free public URL to reproduce a real 303 response (CORS enabled, optional ?delay=ms up to 5000).

https://castov.com/api/mock/303

303 vs similar status codes

303 vs 302 Found

303 explicitly tells the client to follow up with GET (Post/Redirect/Get). 302 is ambiguous about the method for historic reasons.

Frequently Asked Questions

What does HTTP Status 303 mean?
Directs the client to fetch the resource at another URI using a GET request.
Why am I getting a 303 status code?
The Post/Redirect/Get pattern: after a successful POST form submission, the server redirects to a result page.
How do I fix a 303 See Other error?
Use 303 after POST to prevent duplicate form resubmissions on browser refresh.
What is the difference between 303 See Other and 302 Found?
303 explicitly tells the client to follow up with GET (Post/Redirect/Get). 302 is ambiguous about the method for historic reasons.
How can I test how my app handles a 303 response?
Send a request to https://castov.com/api/mock/303 — it returns a real 303 See Other response with CORS enabled. Add ?delay=2000 to simulate a slow server.

Other 3xx status codes

300301302303304307308

Browse the full HTTP status codes directory or troubleshoot terminal errors in the Error Fix Encyclopedia.