Kotlin is becoming a mature and established back-end language. The maturity of a language is not only measured by its features but also by its community and ecosystem. Kotlin’s ecosystem for server-side development is growing very fast. Coming from the Java development side, Spring would be a default fallback option to build your application. While Spring is also hopping on the Kotlin train, the rest of Kotlin’s ecosystem is growing fast. More and more new frameworks are popping up implementing different points of view on how to build your service. Those new frameworks might change our ways of developing back-end applications. Let’s have a look out there!