What is the post/redirect/get pattern?
After handling a form POST, the server answers 303 pointing to a normal page. The browser loads it with GET, so a refresh repeats only the harmless GET instead of resubmitting the form.
HTTP 303 SEE OTHER
Go GET a different URL, typically after a form POST (post/redirect/get). 303 belongs to the 3xx redirection class and is defined in RFC 9110.
Loading the workbench.
About HTTP 303
What Does HTTP 303 See Other Mean?
Go GET a different URL, typically after a form POST (post/redirect/get). The code is registered with IANA and defined in RFC 9110.
Redirection: the client must take another step to finish the request. Every code from 300 to 399 shares that general meaning, so a client that does not recognise 303 must treat it like 300.
When Do You See a 303 Response?
303 See Other tells the client to fetch a different URL with GET, whatever method it used originally. Its main use is the post/redirect/get pattern: after a form submission succeeds, the server redirects to a results or confirmation page, so pressing reload does not resubmit the form and the back button behaves sensibly. APIs also use it to point from a finished asynchronous job to the resource that holds the result.
How Do You Handle a 303?
Servers must provide a Location header with the URL to GET. The target page should be safe to reload and bookmark. Clients following a 303 must switch to GET and drop the request body, which every browser does. Note that 303 itself is not cacheable by default, and the target is a separate resource with its own caching rules, so set those on the page being redirected to.
What Does a 303 Response Look Like?
HTTP/1.1 303 See Other
Location: /orders/8841/confirmation
Content-Length: 0303 is not cacheable by default: a browser or CDN stores it only when Cache-Control or Expires explicitly allows it.
To inspect a real one without sending it anywhere:
- Copy the response headers from your browser Network tab, or from
curl -i. - Paste them into the Header decoder to see every header explained.
- Check caching in the Cache lane and the Location target in the decoder.
Which Status Codes Are Related to 303?
- 302 Found: A temporary redirect. Clients may change POST to GET; use 307 to forbid that.
- 307 Temporary Redirect: A temporary redirect that keeps the method and body: a POST stays a POST.
- 201 Created: A new resource was created. The Location header usually points to it.
- 202 Accepted: The request was queued but not finished. Common for background jobs.
Browse every code on the HTTP status codes page.
What Other Lanes Are in the Reference Section?
- HTTP status codes: Every IANA-registered status code, with a page per code.
- MIME types: File extensions to Content-Type, searchable both ways, plus a Content-Type parser.
- HTTP methods: GET, POST, PUT, PATCH, DELETE and the rest: safe, idempotent, cacheable.
Elsewhere in 2http: Header decoder, Cookie decoder, Cache-Control decoder, CORS checker, User-agent parser, and all eleven lanes on the 2http home page. Part of the 2suite.io privacy-first ecosystem.
Frequently Asked Questions
Is 303 a permanent or temporary redirect?
Neither in the usual sense. It does not say the resource moved; it says the answer to this request can be found by GETting another URL.
Is HTTP 303 an error?
No. 303 is a redirection response, not an error.
Is a 303 response cacheable by default?
No. Caches store a 303 only when Cache-Control or Expires explicitly allows it.
How Can You Verify That Nothing Leaves This Browser?
You do not have to take our word that your headers stay here. Developer tools show every request a page makes, so you can watch this page work and confirm that nothing is sent. The check takes under a minute.
- Open your browser developer tools with
F12, orCmd+Option+Ion a Mac, and select the Network tab. - Reload the page and let it finish. You will see the page's own files, its web fonts, and one anonymous page-view request. Nothing has been typed yet, so none of them can contain your headers.
- Click the clear icon in the Network tab so that the log is empty.
- Paste real headers into any lane and read the result.
- Look at the Network tab again. It is still empty. For extra proof, turn on offline mode after the page loads and every lane keeps working.
Only two things can add a line to that log, and neither carries your headers. Submitting the feedback form sends the vote and comment you typed. Typing characters in a script the page has not displayed yet, such as Cyrillic or Greek, can make the browser fetch the matching font file, and that request names only the font.
2http never sends a request on your behalf: the request builder writes code for you to run, and the meta inspector reads source you paste instead of fetching a URL. The production site also sends a Content-Security-Policy header that tells your browser to refuse connections to anywhere except this site and the anonymous analytics endpoint.