JetBrains Amper build tool adds Compose Hot Reload

JetBrains has released Amper 0.8.0, an update to the build tool for Java and Kotlin that adds support for Compose Hot Reload. Amper 0.8.0 also adds support for custom Kotlin compiler versions and for JavaScript and WebAssembly (Wasm) targets.

Amper is still experimental software under active development. The now-supported Compose Hot Reload automatically loads UI code changes in a Compose Multiplatform application, allowing developers to see the results instantly without having to restart the application. 

Amper 0.8.0 also brings support for custom Kotlin compiler versions, allowing developers who are eager to try new Kotlin compilers before the next Amper release to customize the Kotlin compiler version with a simple setting. Only versions 2.0.0 and above of the Kotlin compiler are supported with this capability, JetBrains said.

Amper also now supports the js, wasmJs, and wasmWasi target platforms, though these application product types remain very basic for now, JetBrains said. Further, the jvm/app and android/app modules have been simplified to only support src, while  the @jvm qualifier is no longer permitted in module.yaml files.

Also introduced is a new, dedicated product type jvm/lib for JVM-only libraries, which offers the same benefits and better conveys intent, JetBrains said.

Announced October 3, Amper 0.8.0 can be accessed from GitHub. Updates to existing projects can be done by running./amper update. For full support for the latest Amper features, developers can use the IntelliJ IDEA 2025.3 EAP IDE or a newer version.

Other new features and improvements in Amper 0.8.0:

Gradle-based Amper has been removed. There will be no further releases of Amper as a Gradle plugin after 0.7.0, JetBrains said. Work will be done on a different solution for gradual migration from Gradle projects in the future.

Developers can set Amper to consider the Maven local repository as a regular repository to resolve from so users can depend on local artifacts.

When creating new directories in a new Amper module, developers now can choose from several predefined options depending on platforms.

A new CLI command,./amper show dependencies, allows users to view the dependency graph of a module.