Your Prototype Is Not Being Honest With Your Users (And Here’s How To Fix It)

This article is a sponsored by ProtoPie There’s a moment in almost every usability session where a participant pauses at the login screen, types something, and glances up: checking whether they’re “doing it right.” That pause is a clear sign. They’ve already clocked that this isn’t a real app, and every data point collected after that moment is filtered through that awareness. In financial product testing, the problem is sharper. Finance users are trained to notice when something feels off: a balance that doesn’t add up, a field that accepts anything. When a banking prototype skips real authentication, participants don’t just disengage; they stop mid-session to flag it. The team walks away with findings that reflect how users behave in a demonstration, not in a real product. The fix is narrower than you’d think. Identify the moment where participant trust is established and make that interaction real. In a banking app, that moment is the login. This tutorial builds it: credentials that validate, a live error state, and a biometric animation that feels native — no code required. What We’re Building: A Login That Behaves Like A Shipped Product The login flow, built around Pie Bank, a mobile banking prototype, includes functional text inputs, a masked password field, credential validation, a live error state, and a Face ID animation timed to feel indistinguishable from iOS. What you’ll need: A login UI from Figma (or any supported design tool) ProtoPie Studio — free to start , everything in this tutorial works on the free plan A Lottie file for the Face ID animation ( this one is what we used) The finished Pie Bank prototype file — download it to follow alongside, or use it as a reference after you build Step 1: Import From Figma Choose Scene, Not Flattened In Figma, open the ProtoPie plugin with your login frame selected and choose Scene when exporting. Flattened collapses everything into a single image; Scene preserves your layer hierarchy so every element arrives in