JsonFeature

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Processes the request and the response payload as JSON, serializing and de-serializing them using a specific serializer: JsonSerializer.

val client = HttpClient(HttpClientEngine) {
    install(JsonFeature)
}

You have a full example using JSON.

This feature is defined in the class io.ktor.client.features.json.JsonFeature in the artifact io.ktor:ktor-client-json:$ktor_version.

dependencies {
    compile "io.ktor:ktor-client-json:$ktor_version"
}

dependencies {
    compile("io.ktor:ktor-client-json:$ktor_version")
}

<project>
    ...
    <dependencies>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-client-json</artifactId>
            <version>${ktor.version}</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</project>

Serializers

The JsonFeature has a default serializer (implicitly obtained or by calling defaultSerializer()) based on a ServiceLoader on JVM (supporting Gson or Jackson depending on the artifact included), and a serializer based on kotlinx.serialization for Native as well as for JavaScript.

You can also get the default serializer by calling io.ktor.client.features.json.defaultSerializer()

Gson

val client = HttpClient(HttpClientEngine) {
    install(JsonFeature) {
        serializer = GsonSerializer()
    }
}

To use this feature, you need to include io.ktor:ktor-client-gson artifact.

Jackson

val client = HttpClient(HttpClientEngine) {
    install(JsonFeature) {
        serializer = JacksonSerializer()
    }
}

To use this feature, you need to include io.ktor:ktor-client-jackson artifact.

Kotlinx.Serialization

val client = HttpClient(HttpClientEngine) {
    install(JsonFeature) {
        serializer = KotlinxSerializer()
    }
}

To use this feature, you need to include io.ktor:ktor-client-json-jvm artifact on the jvm.