Fake Door Test

Why this matters for your decision

Whether it is a new feature, a new tariff or a different price: a Fake Door Test delivers a behavioural signal instead of a declaration of intent. Anyone who clicks on an offer that does not yet exist shows interest through an action. That is more informative than the question 'Would you use this?', to which many people kindly answer yes.

How robust the signal is depends on how the test is built. A button without a price measures curiosity. A complete offer with a price, several variants and a measurement point shortly before sign-up measures purchase intent or sign-up intent.

One method, many names

Several terms are in circulation in companies for the same approach. They almost always mean the same thing: you show real people an offer that does not yet exist and measure whether they choose it.

• Pretotyping: the umbrella term, combining 'pretend' and 'prototype'.
• Painted Door Test: the image of a painted door that looks real but does not yet lead anywhere.
• Smoke Test: common above all in marketing and start-ups.
• Fake Door Test: common above all in product teams for digital products.
• Proto-selling: widespread above all in the US.

There are nuances between the terms, for example whether the test runs inside an existing app or on a dedicated offer page. What counts for the decision, however, is not the name but how the test is built: with a price, with several variants, with an isolated variable and with a measurement point close to the decision.

How Horizon implements it

Horizon shows real consumers a complete offer with a price on a realistic offer page via Google and Meta ads. Up to six variants run in parallel and differ only in the attribute the decision is about. What is measured is the last binding click before the reveal.

A Fake Door Test in your own app remains a good tool for feature questions among existing users. If an offer is also meant to reach people who do not yet use the product, or if the question is about price, a test outside your own channels is needed.

Example

A bank is considering offering a paid travel insurance package with its current account. A button in the account area of the app reaches a click-through rate of 6% within two weeks. That shows interest, but says nothing about the price.

A subsequent test shows the package at €4.90 and €7.90 per month to people outside the customer base. Measured sign-up intent is 2.3% and 1.4%. Both tests follow the same logic, and the second provides the basis for the pricing decision.

Limits

A click without a price does not separate curiosity from purchase intent. Tests with existing users only allow limited conclusions about new customers. And the reveal should happen immediately and in a friendly way, so that trust in the product and the brand is preserved.