kotlin-tooling-kotlin-toolchain

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), …

dependencies:
  - org.example:artifact:1.0.0           # Maven coordinates
  - //other-module                       # Module dependency (relative path from the project root)
  - $libs.ktor.client                    # From version catalog
  - bom: io.ktor:ktor-bom:2.2.0          # BOM import
  - org.example:foo:1.0.0: exported      # Exposed to dependents (like Gradle api())
  - org.example:bar:1.0.0: compile-only
  - org.example:baz:1.0.0: runtime-only

test-dependencies:
  - io.mockk:mockk:1.13.0

settings:
  jvm:
    mainClass: org.example.MainKt   # Default: main() in main.kt
    jdk:
      version: 21
  kotlin:
    languageVersion: 2.0
  compose:
    enabled: true

test-settings:
  kotlin:
    languageVersion: 2.0