Kotlin serializer for TOON (Token-Oriented Object Notation).

To learn about the TOON format and why you should use it read the official website:

• https://toonformat.dev/
• TOON specification: https://github.com/toon-format/spec.

• Full TOON 3.0.1 Spec Support - Complete implementation of the TOON format specification, including tabular arrays, key folding, and delimeters. 400+ tests.
• Kotlin Multiplatform - Supports JVM and JavaScript targets. Others can be added on request.
• Maven Central - Published to Maven Central for easy dependency management with Gradle and Maven.
• Fully Featured
  • Encode Kotlin data classes to TOON
  • Encode JSON to TOON
  • Decode TOON to Kotlin data classes
• Minimal Dependencies - Only depends on kotlinx.serialization, no additional runtime dependencies.
• High Performance - CharArray-based encoding optimized for minimal allocations and fast string operations.
• Flexible Configuration - Configurable delimiters, indentation, and key folding.

Using the Gradle Kotlin DSL:

// build.gradle.kts
dependencies {
    implementation("com.lukelast.ktoon:ktoon:VERSION")
}

Using Gradle Version Catalog:

# gradle/libs.versions.toml
[versions]
ktoon = "VERSION"

[libraries]
ktoon = { module = "com.lukelast.ktoon:ktoon", version.ref = "ktoon" }

// build.gradle.kts
dependencies {
    implementation(libs.ktoon)
}

For multiplatform projects:

// build.gradle.kts
kotlin {
    sourceSets {
        commonMain.dependencies {
            implementation("com.lukelast.ktoon:ktoon:VERSION")
        }
    }
}

Using Maven:

<!-- pom.xml -->
<dependency>
    <groupId>com.lukelast.ktoon</groupId>
    <artifactId>ktoon-jvm</artifactId>
    <version>VERSION</version>
</dependency>

import com.lukelast.ktoon.Ktoon
import kotlinx.serialization.Serializable

@Serializable
data class User(val id: Int, val name: String)

fun main() {
    val encoded = Ktoon.Default.encodeToString(User(1, "Alice"))
    println(encoded)
}

• This library is built to target Java 17.
• You need kotlinx serialization which requires a build plugin.
  • https://github.com/Kotlin/kotlinx.serialization

Check out the demo project in the demo directory for more examples on how to use Ktoon. demo/README.md)

See the development guide for how to do development.