Page Title
kotlinlang.org
What is Kotlin?
Is an OSS statically typed programming language 
that targets the JVM, Android, JavaScript and Native. 
It’s developed by JetBrains. The project started in 2010 
and was open source from very early on. 
The first official 1.0 release was in February 2016.

What is the current version of Kotlin?
The currently released version is 1.2.60, published on 
August 01, 2018.

Is Kotlin free?
Yes. Kotlin is free, has been free and will remain free. 
It is developed under the Apache 2.0 license and the 
source code is available on GitHub.

Is Kotlin an object-oriented language
or a functional one?
Kotlin has both object-oriented and functional constructs. 
You can use it in both OO and FP styles, or mix elements 
of the two. With first-class support for features such as
higher-order functions, function types and lambdas, 
Kotlin is a great choice if you’re doing or exploring 
functional programming.

What advantages does Kotlin give me over the 
Java programming language?
Kotlin is more concise. Rough estimates indicate 
approximately a 40% cut in the number of lines of code.
It’s also more type-safe, e.g. support for non-nullable
types makes applications less prone to NPE’s. Other 
features including smart casting, higher-order functions,
extension functions and lambdas with receivers provide the
ability to write expressive code as well as facilitating
creation of DSL.

Is Kotlin compatible with the Java 
programming language?
Yes. Kotlin is 100% interoperable with the Java programming
language and major emphasis has been placed on making sure 
that your existing codebase can interact properly with 
Kotlin.
You can easily call Kotlin code from Java and Java code from
Kotlin. This makes adoption much easier and lower-risk.
There’s also an automated Java-to-Kotlin converter built
into the IDE that simplifies migration of existing code.

What can I use Kotlin for?
Kotlin can be used for any kind of development, be it 
server-side, client-side web and Android. With Kotlin/Native
currently in the works, support for other platforms such as
embedded systems, macOS and iOS is coming. People are using
Kotlin for mobile and server-side applications, client-side 
with JavaScript or JavaFX, and data science, just to name a 
few possibilities.

Can I use Kotlin for Android development?
Yes. Kotlin is supported as a first-class language on Android.
There are hundreds of applications already using Kotlin for
Android, such as Basecamp, Pinterest and more. For more 
information check out the resource on Android development.

Can I use Kotlin for server-side development?
Yes. Kotlin is 100% compatible with the JVM and as such you
can use any existing frameworks such as Spring Boot, vert.x
or JSF. In addition there are specific frameworks written in
Kotlin such as Ktor. For more information check out the 
resource on server-side development.

Can I use Kotlin for web development?
Yes. In addition to using for backend web, you can also use
Kotlin/JS for client-side web. Kotlin can use definitions
from DefinitelyTyped to get static typing for common 
JavaScript libraries, and it is compatible with existing 
module systems such as AMD and CommonJS. For more 
information check out the resource on 
client-side development.

Can I use Kotlin for desktop development?
Yes. You can use any Java UI framework such as JavaFx, Swing
or other. In addition there are Kotlin specific frameworks
such as TornadoFX.

Can I use Kotlin for native development?
Kotlin/Native is currently in the works. It compiles Kotlin
to native code that can run without a VM. There is a 
Technology Preview released but it is not production-ready
yet, and doesn’t yet target all the platforms that we plan
to support for 1.0. For more information check out the blog
post announcing Kotlin/Native.

What IDEs support Kotlin?
Kotlin is supported by all major Java IDEs including 
IntelliJ IDEA, Android Studio, Eclipse and NetBeans. 
In addition, a command line compiler is available and 
provides straightforward support for compiling and 
running applications.

What build tools support Kotlin?
On the JVM side, the main build tools include Gradle, Maven,
Ant, and Kobalt. There are also some build tools available
that target client-side JavaScript.

What does Kotlin compile down to?
When targeting the JVM, Kotlin produces Java compatible
bytecode. When targeting JavaScript, Kotlin transpiles
to ES5.1 and generates code which is compatible with
module systems including AMD and CommonJS. 
When targeting
native, Kotlin will produce platform-specific code (via LLVM).

Does Kotlin only target Java 6?
No. Kotlin lets you choose between generating Java 6 and 
Java 8 compatible bytecode. More optimal byte code may 
be generated for higher versions of the platform.

Is Kotlin hard?
Kotlin is inspired by existing languages such as Java, C#,
JavaScript, Scala and Groovy. We've tried to ensure that 
Kotlin is easy to learn, so that people can easily jump on 
board, reading and writing Kotlin in a matter of days. 
Learning idiomatic Kotlin and using some more of its advanced
features can take a little longer, but overall it is not a 
complicated language.

What companies are using Kotlin?
There are too many companies using Kotlin to list, but some
more visible companies that have publicly declared usage of 
Kotlin, be this via blog posts, GitHub repositories or talks 
include Square, Pinterest or Basecamp.

Who develops Kotlin?
Kotlin is primarily developed by a team of engineers at 
JetBrains (current team size is 40+). The lead language 
designer is Andrey Breslav. In addition to the core team, 
there are also over 100 external contributors on GitHub.

Where can I learn more about Kotlin?
The best place to start is this website. From there you can
download the compiler, try it online as well as get access
to resources, reference documentation and tutorials.

Are there any books on Kotlin?
There are already a number of books available for Kotlin,
including Kotlin in Action which is by Kotlin team members
Dmitry Jemerov and Svetlana Isakova, Kotlin for Android
Developers targeted at Android developers.

Are there any online courses 
available for Kotlin?
There are a few courses available for Kotlin, including a 
Pluralsight Kotlin Course by Kevin Jones, an O’Reilly Course
by Hadi Hariri and an Udemy Kotlin Course 
by Peter Sommerhoff.

There are also many recordings of Kotlin talks available on 
YouTube and Vimeo.

Does Kotlin have a community?
Yes. Kotlin has a very vibrant community. Kotlin developers
hang out on the Kotlin forums, StackOverflow and more 
activelyon the Kotlin Slack (with close to 7000 members as 
of May 2017).

Are there Kotlin events?
Yes. There are many User Groups and Meetups now focused 
exclusively around Kotlin. You can find a list on the
web site. In addition there are community organised Kotlin
Nights events around the world.

Is there a Kotlin conference?
Yes. The first official KotlinConf, taking place in 
San Francisco
2-3 November 2017. Kotlin is also being covered 
in different conferences worldwide. You can find
a list of upcoming talks on the web site.

Is Kotlin on Social Media?
Yes. The most active Kotlin account is on Twitter. 
There is also a Google+ group.

Any other online Kotlin resources?
The web site has a bunch of online resources, 
including Kotlin Digests by community members,
a newsletter, a podcast and more.

Where can I get an HD Kotlin logo?
Logos can be downloaded here. Please follow 
simple rules in the
guidelines.pdf inside the archive.
Kotlin Language (for PC)
