JSON support using Jackson

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The Jackson feature allows you to handle JSON content in your application easily using the jackson library.

This feature is a ContentNegotiation converter.

This feature is defined in the class io.ktor.jackson.JacksonConverter in the artifact io.ktor:ktor-jackson:$ktor_version.
dependencies { implementation "io.ktor:ktor-jackson:$ktor_version" }
dependencies { implementation("io.ktor:ktor-jackson:$ktor_version") }
<project> ... <dependencies> <dependency> <groupId>io.ktor</groupId> <artifactId>ktor-jackson</artifactId> <version>${ktor.version}</version> <scope>compile</scope> </dependency> </dependencies> </project>

Basic usage

To install the feature by registering a JSON content convertor using Jackson:

install(ContentNegotiation) {
    jackson {
        // Configure Jackson's ObjectMapper here

The jackson block is a convenient method for:

register(ContentType.Application.Json, JacksonConverter(ObjectMapper().apply {
    // ...


Inside the jackson block, you have access to the ObjectMapper used to install the ContentNegotiation. To give you an idea of what is available:

install(ContentNegotiation) {
    jackson {
        dateFormat = DateFormat.getDateInstance()
        convertValue(..., ...)