He got up at 5 a.m. for his app — now it's his full-time business

Czech developer Jan Číslinský spent ten years running a side project — the app Zvednout to? (“Should I pick up?”), which tells iPhone users whether it's worth answering a call from an unknown number. A few years ago he bought out his colleague's share, overhauled the product completely, and recently left his corporate career for good to work on the app full-time.

The idea was born back in 2016, when Apple first allowed third-party developers to identify incoming calls. A colleague of Číslinský's at the company Etnetera suggested making such an app — he brought a database of phone numbers, while Číslinský took on the development. That's how Zvednout to? came about — the first Czech app of its kind in the App Store.

In 2019, Číslinský moved from Etnetera to the consulting firm JLL, where he rose from developer to manager. Meanwhile, the app got only leftover attention: for years it saw no updates, and only around a hundred people a month downloaded it for a one-time fee of 99 crowns. Even so, it steadily brought in 5,000–10,000 crowns a month without any active involvement from its creator.

Realizing the potential of a project that “earned money on its own,” Číslinský bought out his partner's share and took development seriously. He spent a year completely reworking the app, and two years ago dropped one-time payments in favor of a subscription model — now around 300 crowns a year. Despite some initial unhappy reviews, distrust quickly gave way to growth: many users signed up right away for an annual subscription at a discounted price, and within a couple of days Číslinský had earned a sum comparable to what he'd paid for his colleague's share.

So that he no longer had to get up at five in the morning for a side project but could work on it full-time, Číslinský added an AI-based feature to the app: a virtual assistant can now answer calls from unknown numbers itself and, within seconds, summarize the gist of the conversation for the user.

Today the app's average monthly revenue (before taxes, Apple's commission and development costs) is around 9,000 dollars (190,000 crowns), and for this year Číslinský is aiming to double that figure.