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Fake Door Test

Put a button or link for a non-existent feature and measure how many people try to use it.

Why

The fake door test measures revealed demand with zero build cost. You add a button or menu item for a feature you have not built, and when users click it you show a "coming soon" message and log the click. The click-through rate tells you what fraction of your existing users actually want that feature — information that is almost impossible to get from surveys (where everything sounds nice) or roadmaps (where the loudest users win). It is the single most honest signal of feature-level demand available.

When

When you already have a live product with traffic and are considering a new feature. Takes 1-2 days to add, 1-2 weeks to collect clicks. Do not use on a brand-new product with no users.

How

1. Choose the feature to test
   - Pick one you are genuinely unsure about (not one you will build anyway)
   - Define the placement: where in the UI would it naturally live?

2. Add the fake entry point
   - Button, menu item, or link with the real label you would use
   - Make it look identical to how a real feature entry would look

3. Handle the click
   - Show a "coming soon" / "notify me" modal
   - Log: user ID, timestamp, the page they were on
   - Optionally capture email for a waitlist

4. Calculate demand
   - CTR = clicks / impressions of the fake door
   - Compare to other feature entry points' CTRs for context
   - High CTR (> 10% of a known-popular feature) → build it
   - Low CTR → deprioritize or kill

5. Follow up
   - Email waitlist signups when you ship — they are your first power users

Example

Existing product: a markdown notes app (50k MAU).
Proposed feature: "AI summarize this note" button in the editor toolbar.

Fake door (2 days to add):
  - Added a "Summarize" button next to "Share"
  - On click: "This feature is coming soon — want early access?" + email field
  - Ran for 2 weeks

Results:
  - 12,400 impressions, 1,340 clicks (10.8% CTR)
  - 890 emails captured
  - For comparison: the "Share" button has 14% CTR

Decision: 10.8% is 77% of the popular Share button → strong demand → build it.

Common Problems

  • ⚠Leaving the fake door up too long — users who click and get nothing lose trust; cap it at 2-3 weeks and ship or remove.
  • ⚠Placing the fake door in an unnatural spot — if users do not see it, you get a false negative; put it where the real feature would live.
  • ⚠Not comparing to a baseline CTR — 5% sounds low but might be high for your UI; always compare to a known feature's CTR.
  • ⚠Testing too many fake doors at once — users get confused and you cannot attribute clicks clearly; test one at a time.

Best Practices

  • ✓Capture emails on the "coming soon" modal — this gives you a launch list and a second signal (how many leave an email vs just click).
  • ✓Tell users honestly in the modal that the feature is being considered, not definitely coming — this maintains trust.
  • ✓Segment the click data by user cohort (new vs power users) — power-user clicks are a stronger signal than drive-by clicks.
  • ✓Combine with a short inline survey on the modal: "what would you use this for?" — 1 open question gives qualitative context to the CTR.