That's super awesome... having worked for years (with long breaks admittedly) on the project, since I finished university and now during #Hacktoberfest getting the first contributions 🙂 I'm still not sure if it would be okay to add a Kotlin dependency to the core. However, we could simplify the APIs and probably even add a great DSL 🙂 That said the REST-API is written in Kotlin (sirix-rest-api module) and I really love Kotlin, even if I'm pretty new to Kotlin.