postredirectget

Postredirectget, commonly known as the Post/Redirect/Get (PRG) pattern, is a web development technique used to prevent duplicate form submissions and to provide a stable, bookmarkable URL after a form submission. The pattern works by having the client submit a form via HTTP POST, after which the server processes the data and returns a redirect response to a URL that uses HTTP GET. The browser follows the redirect and performs the GET request on the redirected URL, and the resulting page is rendered. Because the final page is retrieved with GET, reloading the page or pressing the back button does not resubmit the form data.

Typically the redirect is implemented with a 303 See Other status code, which clearly indicates that the following request should be a GET. Some servers or clients may use 302 Found, but 303 is preferred for unambiguous GET semantics after a POST. The pattern also enables the use of transient messages, such as “success” notices, by storing them in the user’s session (often referred to as a flash message) and displaying them on the redirected page.

Benefits of PRG include preventing duplicate submissions, producing a clean, shareable URL for the results, and enabling user-facing notifications without resubmitting data. Limitations include an extra round trip due to the redirect, and the pattern may be less suitable for certain API endpoints or highly dynamic multi-step workflows. Many web frameworks implement PRG as a common post-submission strategy to improve reliability and user experience.