design ethics
Sneaking
What is the sneaking dark pattern?
Sneaking is a deceptive pattern that hides, disguises or delays information the user would object to, revealing it only once they're committed. Extra items slipped into a basket, fees that appear at the final step, or a subscription buried in a "free" sign-up all work by withholding the bad news until backing out feels too costly.
Also known as: sneaking, sneaking dark pattern, hidden costs
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The demo
The same purchase, checked out two ways. One shows the full cost from the start; the other keeps it low until the last step, then springs the extras. Walk through each and watch where the truth lands.
What this demo shows (text version)
The same item is bought two ways. In the sneaky checkout the headline price looks low, and only at the final step do delivery, a pre-ticked warranty and a "service fee" appear, pushing the real total well above what you expected - at the point where abandoning feels like wasting your effort. In the honest checkout the same total, with every line itemised and any extra clearly opt-in, is shown from the very start, so you decide with full information.
That's sneaking: concealing costs, added items or commitments until the user is committed, so sunk effort pressures them into accepting. The final price is identical - only the timing differs. Honest design shows the full cost and every commitment at the point of decision, because hiding a fact that would change the choice is deception, not delight.
Sneaking wins by timing: it conceals something you'd reject - a cost, an add-on, a commitment - until you've sunk enough effort that quitting feels worse than accepting. Hidden checkout fees, an item pre-added to your cart, "free" trials that quietly roll into paid plans. It exploits sunk cost and the momentum of a nearly-finished task. The honest alternative is simple and usually not much harder to build: show the full cost and every commitment up front, so consent is informed. If a fact would change someone's decision, hiding it until the end isn't a UX flourish - it's deception.
Up front, you saw the real total and decided freely. Sneaked in at the last step, the same charge catches you mid-commitment, when abandoning feels like wasting all that effort - so you grudgingly accept. Nothing about the price changed; only when you were told. That timing is the whole trick, and it's why honest design puts the full cost where the decision is made, not after it.
Sneaking covers several specific patterns: sneak-into-basket (adding an item the user didn't choose), hidden costs (fees revealed only at the final checkout step), hidden subscription (a one-off purchase or free trial that quietly becomes recurring), and bait-and-switch timing where the real terms surface late. The common thread is concealment of something the user would likely decline if shown it earlier.
It works by exploiting commitment and sunk cost: once someone has entered details, configured an order or invested several steps, the effort already spent makes abandoning feel wasteful, so they accept a charge or term they'd have refused up front. The near-complete task creates momentum that the pattern cashes in at the last moment.
The fix is radical transparency and good timing: surface total costs, added items and recurring commitments at the point of decision, not after it; make any pre-selected extras opt-in and obvious; and never let a "free" path silently convert to paid. Regulators increasingly treat hidden costs and drip pricing as unlawful, but beyond compliance it's simply a matter of honest consent - if a fact would change the choice, show it before the choice is made.