RxKotlin is a Kotlin-specific wrapper and extension for RxJava, making it easier to use reactive programming in Kotlin applications. It provides Kotlin-friendly APIs, extension functions, and utilities for working with reactive streams in a more idiomatic manner. Based on extension function, null safety, and conciseness features, there are significant differences between RxJava and RxKotlin, as shown in Table 11-1. Kotlin can be integrated and tested with existing Java. Kotlin’s strong interoperability with Java enables the use of RxJava and RxKotlin to write reactive programs. RxJava and RxKotlin libraries from the ReactiveX (Rx) project are used to add reactive capabilities [1]. Reactive libraries, such as Reactor, can also be used. At the same time, coroutines and suspension functions are used as a reactive extension in Kotlin [2]. RxJava serves as the backbone for other ReactiveX JVM ports, including RxScala and RxKotlin [3]. RxKotlin utilizes the majority of RxJava operators, as outlined on its GitHub page for Kotlin. RxAndroid is RxJava bindings for Android [4].