> For the complete documentation index, see [llms.txt](https://fuel.gitbook.io/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fuel.gitbook.io/documentation/deserialization/fuel-kotlinx-serialization.md).

# Kotlinx-Serialization

The kotlinx-serialization extension package for [`Fuel`](broken://pages/-LS8kbBJjT2_gwYkij4g).

## Installation

You can [download](https://bintray.com/kittinunf/maven/Fuel-Android/_latestVersion) and install `fuel-kotlinx-serialization` with `Maven` and `Gradle`. The kotlinx-serialization package has the following dependencies:

* [`Fuel`](/documentation/core/fuel.md)
* [KotlinX Serialization](https://github.com/Kotlin/kotlinx.serialization#gradle): 1.0.1

```groovy
implementation 'com.github.kittinunf.fuel:fuel:<latest-version>'
implementation 'com.github.kittinunf.fuel:fuel-kotlinx-serialization:<latest-version>'
```

## Usage

```kotlin
@Serializable
data class HttpBinUserAgentModel(var userAgent: String = "")

Fuel.get("/user-agent")
    .responseObject<HttpBinUserAgentModel> { _, _, result -> }
```

This is by default strict and will reject unknown keys, for that you can pass a custom Json instance `Json(strictMode = false)` or use a built-in alternate like `Json.nonstrict`

```kotlin
@Serializable
data class HttpBinUserAgentModel(var userAgent: String = "")

Fuel.get("/user-agent")
    .responseObject<HttpBinUserAgentModel>(json = Json.nonstrict) { _, _, result -> }
```

`kotlinx.serialization` can not always guess the correct serialzer to use, when generics are involved for example

```kotlin
@Serializable
data class HttpBinUserAgentModel(var userAgent: String = "")

Fuel.get("/list/user-agent")
    .responseObject<HttpBinUserAgentModel>(loader = HttpBinUserAgentModel.serializer().list) { _, _, result -> }
```

It can be used with coroutines by using `kotlinxDeserializerOf()` it takes the same `json` and `loader` as parameters

```kotlin
@Serializable
data class HttpBinUserAgentModel(var userAgent: String = "")

Fuel.get("/user-agent")
    .awaitResponseObject<HttpBinUserAgentModel>(kotlinxDeserializerOf()) { _, _, result -> }
```