This is a text-only chat roulette implementation in pure Kotlin, i.e., both backend and frontend are written in Kotlin. Build & run with ./gradlew run. The application is up when the line [main] INFO ktor.application - Responding at http://0.0.0.0:8080 is logged.
Try it out at https://guarded-waters-49301.herokuapp.com/.
To deploy to Heroku, apply the following configuration to the Heroku application: heroku config:set GRADLE_TASK="installDist". This tells Heroku which Gradle task to run during deployment. The installDist task writes a self-contained version of the application to the directory build/install/chat-roulette/, which can then be started via ./build/install/chat-roulette/bin/chat-roulette.