Fake-door test
(Smoke test)A test where you present an offer or feature that doesn't fully exist yet, to see whether real (or synthetic) demand shows up before you build it.
Testing demand before the door actually opens.
A fake-door test presents people with something that looks like a real offer or feature — a landing page, a signup button, a pricing tier — before it's actually been built, to measure how many people try to walk through the "door" before you invest in building it for real.
Why it matters
It's one of the more honest ways to test demand, because it measures an actual behavioral signal — a click, a signup attempt — rather than a stated opinion about whether someone would be interested. Stated interest and real behavior often diverge, and a fake-door test is designed to catch that gap.
How it relates to synthetic panel testing
A synthetic panel test and a fake-door test answer different questions at different stages. A panel test asks a described audience for their reaction to an idea before anything is built; a fake-door test measures real behavior against something that looks real, one step closer to launch. Using a panel test first can help you decide which idea is worth building a fake door for at all.