The popularity of Kotlin can be seen in a number of ways. GitHub's 2018 The State of the Octoverse survey listed Kotlin as the number one fastest growing language by contributors, seeing a 2.6x increase in contributors over the previous year.
JetBrains is currently planning their third KotlinConf, which has welcomed over 1,200 attendees at each of the earlier events. The reception at the first event was so positive, and demand overseas was so high, that in 2018, the event was moved from San Francisco to Amsterdam.
As more and more developers are turning to Kotlin, we are now seeing an increase in learning tools as well. Companies such as Google and Udacity have partnered to develop Kotlin training courses. JetBrains now offers a Kotlin training certification for individuals or companies that want to certify the quality of their Kotlin instruction. Developers are writing and speaking about Kotlin all over the world at meetups, conferences, and on podcasts, webinars, and so on. Much of this is new over the past two years, and all indicators suggest that this will only increase as more and more organizations and individuals start using Kotlin in their projects.