HTML5 form submission lacks built-in deduplication for non-idempotent POST resubmission
Limits of native duplicate prevention The HTML Living Standard defines form submission with method="POST" as non-idempotent but does not specify any browser-level mechanism to prevent duplicate server-side processing when a user manually resubmits—whether by refreshing a POST result page, navigating back/forward, or restoring a page from bfcache. The spec pr
html5