OpenAPI Ktor Client Generator

A powerful Gradle plugin that transforms OpenAPI v3 specifications into production-ready Kotlin Ktor client code. You can customize the generated clients and models to match your project's specific needs.

Prerequisites

• JDK 17+
• Gradle 9+

Installation

Add the plugin to your build.gradle.kts:

plugins {
    id("org.litote.openapi.ktor.client.generator.gradle") version "<last version>"
}

Where <last version> is

Configuration

Configure the plugin in your build.gradle.kts:

apiClientGenerator {
    generators {
        create("openapi") { // Task name: generateOpenapi
            outputDirectory = file("build/generated")
            openApiFile = file("src/main/openapi/openapi.json")
            basePackage = "com.example.api"
            // Optional: Add more configuration options below
        }
        // You can create multiple generators with different names
    }
}

For a complete example with all available options, see e2e/build.gradle.kts.

Usage

Run the generation task directly:

./gradlew generateOpenapi

Or trigger generation as part of the build process:

./gradlew build

This will generate Ktor client code based on your OpenAPI specification and plugin configuration. The generated code will be placed in the configured outputDirectory.

Configuration Properties

Root properties

Property	Description	Default value	Allowed values
generators	Generators configuration	{}	Any configuration
skip	Skip all clients generation	false	Boolean

Generator properties

Property	Description	Default value	Allowed values
openApiFile	OpenAPI v3 source file	file("src/main/openapi/${name}.json")	Any existing OpenAPI file
outputDirectory	Target directory for generated sources (a src/main/kotlin subdirectory will be added)	file("build/api-${name}")	Any relative directory
basePackage	Base package for all generated classes	org.example	Any valid package name
allowedPaths	Restrict generation to a subset of OpenAPI paths	empty (all paths are generated)	Any subset of paths defined in the OpenAPI spec
modulesIds	Extra generation modules to enable	Empty (no modules)	UnknownEnumValueModule, LoggingSl4jModule
skip	Skip this client generation	false	Boolean

Project Structure

• generator/ - Core code generation logic and OpenAPI parsing
• gradle-plugin/ - Gradle plugin implementation and task integration
• e2e/ - End-to-end test project(s) with example configurations
• module/ - Optional modules for extended functionality
• shared/ - Shared utilities and code used across modules