When Valeriy Ovechkin, a Square software engineer, started on the team for Square's restaurant app, Caviar, it was written completely in Java.
Java, one of the most widely used programming languages, was created by Sun Microsystems, the company later acquired by Oracle, and commonly used to write databases and Android apps.
But Java, which dates back to 1995, can be a bit clunky, developers say. Increasingly, Android engineers are instead using a newer open-source programming language, Kotlin, to write their apps. As for Caviar, it's now 100% in Kotlin.
"Kotlin in itself is a modern programming language," Ovechkin told Business Insider. "I've seen other features in Kotlin that make development more delightful. Kotlin is easier to pick up and more expressive. Writing the same code in Kotlin usually results in fewer lines of code."
Kotlin has quickly skyrocketed in popularity. It's used by companies like Google, Square, Pinterest, Pivotal, and Atlassian. It's the fastest-growing programming language, according to GitHub, the "Facebook for programmers," growing over 2 1/2 times in the past year. It was voted one of the five most loved languages, according to Stack Overflow, a site for developers to ask and answer questions about code. There are even meetups focused on Kotlin.
"What is interesting with Kotlin is basically it leverages the existing skills of Java developers and finds the right tradeoffs to provide new features and provide things that make Java developers more efficient without going too far," Sébastien Deleuze, a Pivotal engineer, told Business Insider.
