[cutler]

Why not Kotlin as it's arguably closer to Ruby?

[Matthias247]

Maybe Java includes the possibility to use Kotlin? At many teams I know its up to the team to write parts of Java libraries or services within Kotlin since it's mostly an implementation detail. But again - I'm not part of Stripe so I can't talk for them.

[rufugee]

Yeah, I would be interested in the logic here. I'd assume Kotlin to be a far more productive language for ex-rubyists than Java.

Perhaps it's that they don't believe in the future of Kotlin outside of mobile?

[esprehn]

In my experience it's usually JVM at these companies, not specifically Java, and certainly in recent years more and more teams use Kotlin for backend services.