Readdle

Readdle was founded in Odesa in 2007 by four university friends, among them Igor Zhadanov, its CEO. It built apps for the iPhone before the App Store opened and has grown without any outside funding.

Its productivity apps are Documents, PDF Expert, the Spark email client, Scanner Pro, Calendars and Fluix, for iPhone, iPad and Mac and, in Spark's case, Android and Windows too. Readdle counts more than 235 million downloads of its apps.

More than 300 people work at Readdle, from hubs in Odesa, Kyiv, Warsaw, Berlin, Lisbon and London and remotely from some 30 countries. Its apps are written mostly in Swift and Objective-C, and it publishes open-source tools on GitHub, among them a toolchain for building Swift code for Android.