App · 2024
Plinthly
Mortgage calculator for Swiss property ownership with sustainability in mind.
Plinthly
Swiss Sustainable Real Estate Explorer
MAX PRICE
CHF 1'000'000
DOWN PAYMENT
CHF 200'000
EST. MONTHLY
Can I buy?
Get an honest picture of your buying power under Swiss mortgage rules, before you talk to a bank.
Your situation
Combined annual gross income before tax.
Your estimated maximum purchase price
You're capped by your down payment, not your income.
Key Takeaways
You can afford up to CHF 1'000'000.
Capped by deposit: more savings lifts this.
Bring CHF 200'000 up front, at least CHF 100'000 real cash.
Role
Sole Designer & Co-founder
Domain
Fintech / Proptech
Constraint
Solo designer, no budget, 6-week build.
Focus
Financial UX · Sustainability
01 The Setup
Context & Problem
Switzerland has among the highest property prices in Europe, yet mortgage complexity keeps many first-time buyers in the dark. Plinthly set out to demystify Swiss home financing, not just showing affordability, but surfacing the sustainability cost-benefit of each property choice. The business opportunity: buyers who understand long-term costs make better, stickier decisions.
I was the sole designer and co-founder, working without user research budget. The product had to be functional enough to validate with real Swiss homebuyers within 6 weeks, which meant cutting scope ruthlessly.
02 Design Decisions
What We Tried & Why We Pivoted
First version: one big form, one output
The initial approach was a single mortgage calculator with sustainability scores appended at the bottom. Testing with 4 users revealed they didn't reach the sustainability section, the form fatigue killed engagement before the key differentiator appeared.
Pivot: progressive staged input
We restructured into a 3-step flow: basic affordability → property details → sustainability impact. Each step delivered a meaningful output, which kept users engaged. Time-on-page increased measurably across retests.
The subsidy surfacing decision
Swiss cantonal subsidies for green renovations are notoriously hard to find. We debated building a full subsidy database (scope-heavy) vs. a curated 'relevant subsidies for your situation' summary. We shipped the summary with a disclaimer link, it reduced build time by 4 weeks without meaningfully reducing perceived value.
03 Outcomes
Results
12
Swiss homebuyers validated prototype
3×
Longer session time vs. v1
2
Cantonal pilot conversations opened
04 Reflection
What I'd Do Differently
If I started again, I'd interview mortgage brokers earlier. They understand the decision tree better than buyers do, and they're the channel.