Kotlin Concurrency in 2026: kotlinx.coroutines vs RxJava vs Flow — Which One Should You Actually Use?

Wed, 26 Aug 2026 00:00:00 +0000

Kotlin’s launch and async have been the default way to write concurrent code on the JVM since 2018, yet a massive amount of production code — especially Android and legacy JVM services — still runs on RxJava’s observable streams. If you open almost any large Kotlin codebase today, you will find both suspend functions and Observable chains living side by side, and teams disagreeing about whether to migrate. This article settles the argument: here is exactly what kotlinx.coroutines, RxJava, and the coroutines-based Flow API are good at, where each one hurts, and how to migrate without rewriting everything at once.

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Kotlin Concurrency in 2026: kotlinx.coroutines vs RxJava vs Flow — Which One Should You Actually Use?