Also known as trap door testing, painted door testing. (Research and discovery)Fake door testing is a product discovery method used to measure customer interest in a product or feature before it is fully built. Instead of coding the full functionality, teams create the appearance of the feature, for example a button, banner, or landing page, and expose it to users as if it already exists. When users interact with the fake door, such as clicking a button, they are taken to a page explaining that the feature is still in development. This page often includes an option to sign up for email updates, allowing teams to capture explicit signals of interest. The goal of fake door testing is to validate whether an idea resonates with users and assess market demand, helping teams avoid investing time and resources in features that may not deliver value. It is a powerful, low cost way to learn quickly with minimal development risk.