Vocabloot uses shared Kotlin code to power Android, iOS, and its JavaScript website

Vocabloot is a vocabulary-learning app that lets users identify real-world objects via camera and also offers downloadable word decks covering greetings and themed topics across ten languages. As the team built a web-based deck page, they faced a challenge: the website needed the same word-parsing and highlighting logic already written in Kotlin for the mobile apps. Rather than rewriting those rules in JavaScript, the developers used Kotlin Multiplatform to compile the shared logic for the web as well. Across the entire codebase, 85% of the Kotlin — over 79,000 lines — is now shared among Android, iOS, and the website. This approach ensures consistent behaviour, such as word highlighting during audio playback and tap-to-define functionality, across all three platforms.