Kotlin Toolchain

JetBrains' unified CLI for Kotlin (JVM, Android, iOS, multiplatform) and Java projects, in Alpha. Configuration is declarative YAML instead of Gradle build scripts.

Installation

Prefer the project's checked-in wrapper: ./kotlin build needs nothing installed, the wrapper downloads the CLI itself. Install a global CLI only when there is no wrapper (e.g. before kotlin init):

sdk install kotlintoolchain      # SDKMAN (macOS / Linux / WSL)

The kotlin command then auto-provisions its JDK on first use. Other install options (installer scripts, IntelliJ IDEA plugin) live at https://kotlin-toolchain.org/.

If the project root ships wrapper scripts (kotlin / kotlin.bat), the global kotlin detects them and proxies into them, pinning the project to the wrapper's version. Always invoke kotlin from the project root so the wrapper wins; never call a globally installed binary directly when a wrapper exists.

CLI commands

For the detailed list of commands and their options, run kotlin --help or kotlin <command> --help.

Project structure

project-root/
├── kotlin, kotlin.bat     # Local wrappers
├── project.yaml           # Project-level config
├── libs.versions.toml     # Version catalog (Gradle-compatible; root or gradle/)
├── module-name/
│   ├── module.yaml        # Module configuration
│   ├── src/               # Production sources (Kotlin + Java mixed when JVM platform is available)
│   ├── resources/         # Resources (copied into JAR)
│   ├── test/              # Test sources
│   └── testResources/     # Test-only resources
└── another-module/
    ├── module.yaml
    └── ...

project.yaml declares the project's modules and any local build plugins. See references/examples.md for a project-level config example.

module.yaml

product: jvm/app    # jvm/app, jvm/lib, android/app, lib (multiplatform), …