Block Forms is a free Chrome extension developed by Clay, categorized under Browsers and Add-ons & Tools. This extension allows users to block consumer forms specifically from their domain, preventing form completions by users with Gmail accounts. It provides the functionality to rewrite the HTML of pages displaying Gmail forms to show a block message.

Moreover, Block Forms offers JSON Policy management for domain Allowlisting and Blocklisting. Users can specify domains to be allowed or blocked, including the option to block all external domains with the use of ["*"]. The extension ensures that user domains are set in the JSON for proper functionality.