I make iPhone apps.

Type in a distance and EV Cost tells you what the trip costs in a petrol car, what it costs in an electric one, and how much CO₂ you didn’t emit — converted into trees, because kilograms mean nothing to anyone.

It started as a prototype whose result screen just said “Tesla cost”. Four versions later it speaks English, German and Hungarian, charts the comparison with Swift Charts, and has been on the App Store since January 2025. Free. No ads, no tracking, no account.

View on the App Store

LogicLab Kids teaches 7–11-year-olds to reason — patterns, cause and effect, weighing evidence, spotting thinking traps. Each lesson is seven stages, and the AI only shows up at the last one. It is architecturally unable to give answers; the system prompt won’t let it. It asks, the kid thinks.

The hook is Apple’s Family Controls: finishing real practice unshields the entertainment apps for a set time. Parents set the limits and can read every AI–child conversation. There’s an Android twin in Kotlin, and before writing much code I put a paid sign-up page in front of parents at my school: 431 opened it, 48 paid for an app that didn’t exist yet.

It won the national final of the 35th OTIO — Hungary’s science and innovation olympiad — and goes to EUCYS 2026 in Kiel, the EU’s young-scientist final, representing Hungary.

logic-lab.hu ↗

A chat app for exactly two people. Instead of one endless scroll, conversations live in named topic threads — like a chat assistant’s sidebar, but for a relationship. Firestore syncs the two devices live; Cloud Functions keep an “our stats” dashboard that reads in O(1).

Then I kept going until it matched iMessage: reactions, edit and unsend, reply-swipe, read receipts, typing indicators, Live Photos, Face ID lock. It will never be on the App Store, and that’s the point.