History & Evolution of Kotlin

Introduction

Kotlin didn't appear out of nowhere — it grew out of a real engineering company's frustration with its own primary language, and it has evolved deliberately ever since its first public appearance. Understanding that timeline explains many of the design choices you'll encounter as you learn the language, especially its heavy emphasis on Java interoperability.

This lesson walks through the timeline: the problem that sparked Kotlin's creation, its early development at JetBrains, the 1.0 release, Google's pivotal endorsement of Kotlin for Android, and the major features added since then.

The Problem JetBrains Faced

JetBrains, founded in 2000 and best known for the IntelliJ platform that powers IntelliJ IDEA and Android Studio, wrote (and still writes) the vast majority of its own products in Java. By the late 2000s, the company's engineers were running into Java's well-known pain points on a daily basis: excessive boilerplate for simple tasks, no built-in null safety (leading to constant `NullPointerException` crashes), and a language evolving slowly compared to newer JVM languages appearing at the time, like Scala.

JetBrains considered adopting an existing alternative JVM language rather than building their own, but found none that combined fast compilation, full Java interoperability, and a gentle learning curve for existing Java teams. That gap is what led them to start designing their own language.

Birth at JetBrains

Development on what would become Kotlin began internally at JetBrains around 2010. The team's explicit goal was a language that compiled as fast as Java, was strictly compatible with the JVM ecosystem, and fixed Java's biggest ergonomic problems — particularly around null handling and verbosity — without asking developers to abandon their existing Java code or tooling.

Public Announcement (2011)

JetBrains publicly unveiled the project in July 2011 at the JVM Language Summit, under the name "Kotlin," referencing Kotlin Island near St. Petersburg, where a large part of the JetBrains engineering team works — echoing how Java itself was named after the Indonesian island. The language continued to develop through several preview milestones over the following years, with JetBrains actively soliciting feedback from the Java community.

Open Source and Kotlin 1.0 (2016)

Kotlin was open-sourced under the Apache 2.0 license in 2012, well before its first stable release. After years of refinement, Kotlin reached its stable 1.0 milestone on February 15, 2016. Like Go's 1.0 compatibility promise, Kotlin 1.0 came with a long-term backward compatibility commitment, giving companies confidence to adopt it for production code.

Google I/O 2017: Official Android Support

The single biggest turning point in Kotlin's history came at Google I/O in May 2017, when Google announced that Kotlin was now an officially supported language for Android app development, alongside Java. Because Kotlin compiles to the same JVM bytecode Android already used, adopting it required no new runtime and could be done incrementally, file by file, inside existing Java-based Android projects. Adoption among Android developers accelerated rapidly from that point on.

2019: Kotlin-First for Android

In 2019, Google went further still, announcing that Android app development would be "increasingly Kotlin-first" — meaning new Jetpack libraries, sample code, and official documentation would default to Kotlin, with Java support continuing but no longer the primary focus. This cemented Kotlin as the de facto standard language for modern Android development.

Coroutines and Kotlin Multiplatform

Alongside its Android success, Kotlin steadily grew capabilities beyond the JVM. Coroutines — Kotlin's lightweight approach to asynchronous programming, covered later in this course — were introduced experimentally in Kotlin 1.1 (2017) and became stable in Kotlin 1.3 (2018). Kotlin Multiplatform, which lets a single Kotlin codebase share logic across Android, iOS, web, and desktop targets, has matured significantly since, letting teams write business logic once instead of duplicating it per platform.

// A coroutine (previewed in this lesson, covered fully later)
// runs asynchronous code without callback nesting.
suspend fun fetchGreeting(): String {
    return "Hello from a coroutine!"
}

Kotlin Today

Kotlin now ships regular releases with careful attention to backward compatibility, much like Go's own compatibility promise. It remains the dominant language for new Android development, is increasingly used for backend services through frameworks like Ktor and Spring Boot, and continues investing in Kotlin Multiplatform and a faster K2 compiler. It consistently ranks as one of the most loved languages in developer surveys.

Common Mistakes

Best Practices

Frequently Asked Questions

Key Takeaways

Summary

Kotlin grew from JetBrains' internal frustration with Java into the preferred language for Android development and a growing choice for backend services. Next, you'll get your development environment set up by installing Kotlin on your machine.