FF4K - Feature Flags for Kotlin¶

FF4K is a Kotlin Multiplatform (KMP) implementation of the popular FF4J (Feature Flipping for Java) library. It brings robust feature flagging capabilities to the Kotlin ecosystem, supporting multiplatform projects.

Key Features¶

Kotlin Multiplatform: Designed to work across different platforms supported by Kotlin (JVM, Android, Native, etc.).
Type-safe Properties: Strongly typed property definitions (String, Int, Boolean, etc.).
Flipping Strategies: Gradual rollouts, A/B testing, and user targeting with built-in strategies.
Serialization Support: Built-in support for kotlinx.serialization.
Extensible: Easily implement custom storage backends (Redis, SQL, etc.) and custom strategies.
DSL: Intuitive domain-specific language for configuration.

Installation¶

Using Bill of Materials (BOM) - Recommended¶

The BOM ensures that all FF4K modules are using compatible versions.

repositories {
    mavenCentral()
}

dependencies {
    // Import the BOM
    implementation(platform("com.yonatankarp:ff4k-bom:<version>"))

    // Add dependencies without versions
    implementation("com.yonatankarp:ff4k-core")
}

Manual Versioning¶

Alternatively, you can specify the version for each module directly:

repositories {
    mavenCentral()
}

dependencies {
    implementation("com.yonatankarp:ff4k-core:<version>")
}

Quick Start¶

suspend fun main() {
    val ff4k = ff4k {
        features {
            feature("dark-mode") {
                isEnabled = true
                description = "Enable dark mode theme"
            }
        }
    }

    // Check feature status
    ff4k.ifEnabled("dark-mode") {
        // ...
    }
}

Check out the Usage guide for more details.

License¶

This project is licensed under the Apache License 2.0.