303 See Other
Meaning
The response to the request can be found at another URI using the GET method. This is used to direct the client to retrieve a resource at a different URI, often after a POST.
When to Use
When a resource has been created or a command processed via POST/PUT/DELETE, and you want the client to retrieve a confirmation or result from a different URI with a GET.
Example
After submitting a form (POST /submit-form), the server responds with 303 See Other and a Location header to /result-page, instructing the client to GET that URL for the results.
When Not to Use
Do not use for GET requests (since the client can directly retrieve content) or for permanent redirect needs (use 301/308 for those). 303 is typically for redirecting after non-GET methods.
Source
RFC 9110