Most unfortunate when you were looking at trending Kotlin projects on Github that the number of Android based projects is unusually high. If you were to have a look today then you would find the numbers are very different. Here are the Kotlin numbers for 8 June 2017:

• Android Libs/Frameworks: 5
• Android Docs/Apps: 5
• Server-side Libs/Frameworks: 7
• Misc: 8

Don’t forget that Kotlin can interop with Java based server-side libs/frameworks (including ones that have Kotlin specific support, e.g. Vert.x). Important to note that the JVM ecosystem (roughly 85% is server-side based) is SIGNIFICANTLY bigger than the Android ecosystem.

One of Kotlin’s main design goals is two way interop with platform APIs. Currently Kotlin can interop with C (Kotlin Native), JS (Kotlin JS), JVM (Kotlin JVM), and Android (Kotlin JVM) APIs. More emphasis is placed on using existing platform ecosystems rather than developing one specifically for Kotlin itself. That quality makes Kotlin well suited for multi-platform projects (e.g. JVM for server side; web, Android, and iOS clients) where a single language is mainly used (significantly lower maintenance), which can achieve a very high level of native platform integration without having to write huge wrapper APIs (which provide a low common denominator experience/poor platform integration).

Can find some limited information about Kotlin’s multi platform strategy in this video. You might be interested in listening to Mike Hearn’s experience with Kotlin on the server-side in this podcast.