Built with care

A subscription is never the only way in. Every fonszi app can be owned outright - one payment, yours forever, every future update included. No forced renewals, no "trial expired" walls, no meter running while you sleep. If we want your money again, we earn it by shipping something new worth buying.

We don't build a profile of you. No sign-up to track your day, no data sold - ever. Our analytics are anonymous and aggregate: we see which features get used, never who used them. The free tier is ad-supported - that's the honest trade for free - and going Pro removes every ad on every screen. This site itself runs on Umami: cookieless, no personal data, no banner to click.

Your ski days and your workouts are yours - saved on your device and fully usable offline. We run our own backend only for the essentials, like your account and app updates; we never hand your data to a third-party broker, and you're never locked in. If fonszi vanished tomorrow, everything you recorded would still be right there on your phone.

The server side is ours, end to end. Auth, licensing, the APIs your app talks to - we build and run them, not a rented stack of third-party SaaS. Fewer moving parts, no surprise data-sharing, and one team accountable when something breaks.Several Fonszi developer tools are open-source: git-hook-suite, our shared libraries, and the infrastructure we build on. If you can read the code, you don't have to trust our claims. You can verify them.

iOS (Swift & SwiftUI), Android (Kotlin & Compose), Apple Watch & Wear OS, and high-performance web - all sharing one Kotlin Multiplatform core. We specialize in cross-platform codebases where performance can't be compromised.