What If There Was A Digital Wallet For Stamp Cards?
Overview
What is Stack?
Think of all the stamp cards you’ve picked up at new cafés. Where are they now?
Lost? Forgotten? Still in your pocket but probably never get to complete?
What if there were one simple place for all of them?
Stack is a digital wallet that keeps your loyalty stamp cards together and helps you discover nearby businesses that use them.
Problem
It is neither lack of motivation nor interest. It’s the process that’s full of frictions.
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~50%
out of the total loyalty programs per consumer are inactive.
Capital One Shopping
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42%
of consumers said they don’t sign up for loyalty programs because it requires too much effort or is too time-consuming.
ebbo.com
-
82%
of customers who have a brand’s loyalty card saved digitally have actually used it to make a purchase.
Vibes’ 2026 Mobile Consumer Report
Pain points from users
- “Oops, I forgot it at home”
- No nudge or reminder to return
- Too many cards with no system
Pain points from local businesses
- Zero visibility into customer behavior
- No discovery mechanism
- Low completion rate
Personas
Two sides of the same stamp card.
Stamp Card User
Emmi Rantanen
- Struggles to keep track of stamp cards from 5+ local cafés and shops.
- Has never completed a card, even as a daily café visitor. The right one is never in her bag.
- Can’t easily discover other local businesses with stamp cards to support and become a regular at.
Local Business Owner
Jari Korhonen
- Gives away 8–10 free coffees a month, but has no data on how many cards go out or get completed.
- Suspects his best regulars (3 visits a week, ~€50 a month) never redeem a card because they forget or lose it.
- Can’t tell if the program drives profit or just gives free coffee to people who’d come anyway.
Solutions
Introducing Stack
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Manage all stamp cards in one wallet
Imagine Apple Wallet but for your little stamp cards.
Every card from selected business will be added into your wallet for a quick catch up and interaction.
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Scan, Stamp & Reward
Scan directly via the card’s bar code.
Stamp to progress for any purchase.
Earn the reward after completion.
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Business Discovery
A browsable directory of participating businesses, available as a list or map view, filterable by category (café, bakery, salons, bookstores, etc.)
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Push Notifications
Smart, contextual push notifications to drive return visits and reward completion.
Reflection
What I Learnt From Building Stack
This project took me through the full 0-to-1 cycle. It started with defining one core problem, which then shaped every decision that followed, through to building a solution true to that foundation. Along the way, I was constantly challenged by considering every possibility that weights the needs for both end-users and business owners. In the end, it was a very fun experiment for me to be able to turn my daily little problem into a working solution.
