Fuel

The easiest HTTP networking library for Kotlin/Android.

You are looking at the documentation for 2.x.y.. If you are looking for the documentation for 1.x.y, checkout the 1.16.0 README.md

Features

• HTTP GET/POST/PUT/DELETE/HEAD/PATCH requests in a fluent style interface
• Asynchronous and blocking requests
• Download as a file
• Upload files, Blobs, DataParts as multipart/form-data
• Cancel asynchronous request
• Debug logging / convert to cUrl call
• Deserialization into POJO / POKO
• Requests as coroutines
• API Routing

Installation

We offer maven and jitpack installations. Maven via bintray only has stable releases but jitpack can be used to build any branch, commit and version.

Maven

You can download and install Fuel with Maven and Gradle. The core package has the following dependencies:

• Kotlin -
• Result - 2.2.0

  //core
  implementation 'com.github.kittinunf.fuel:fuel:<latest-version>'
  
  //packages
  implementation 'com.github.kittinunf.fuel:<package>:<latest-version>'

Each of the extensions / integrations has to be installed separately.

Package	Description
fuel	Core package
fuel-android	Android: Automatically invoke handler on Main Thread when using Android Module
fuel-coroutines	KotlinX: Execution with coroutines
fuel-forge	Deserialization: Forge
fuel-gson	(De)serialization: Gson
fuel-jackson	Deserialization: Jackson
fuel-json	Deserialization: Json
fuel-kotlinx-serialization	(De)serialization: KotlinX Serialization
fuel-livedata	Android Architectures: Responses as LiveData
fuel-moshi	Deserialization: Moshi
fuel-reactor	Reactive Programming: Responses as Mono (Project Reactor 3.x)
fuel-rxjava	Reactive Programming: Responses as Single (RxJava 2.x)
fuel-stetho	Utility: Debug utility for Android on Chrome Developer Tools, Stetho

Jitpack

If you want a SNAPSHOT distribution, you can use Jitpack

repositories {
  maven(url = "https://jitpack.io") {
    name = "jitpack"
  }
}

dependencies {
  //core
  implementation(group = "com.github.kittinunf.fuel", name = "fuel", version = "-SNAPSHOT")
  
  //packages
  // replace <package> with the package name e.g. fuel-coroutines
  implementation(group = "com.github.kittinunf.fuel", name = "<package>", version = "-SNAPSHOT")
}

or

dependencies {
  //core and/or packages
  // replace <package> with the package name e.g. fuel-coroutines
  listof("fuel", "<package>").forEach {
    implementation(group = "com.github.kittinunf.fuel", name = it, version = "-SNAPSHOT")
  }
}

Configuration

• group is made up of com.github as well as username and project name

• name is the subproject, this may be any of the packages listed in the installation instructions eg. fuel, fuel-coroutines, fuel-kotlinx-serialization, etc

• version can be the latest master-SMAPSHOT or -SNAPSHOT which always points at the HEAD or any other branch, tag or commit hash, e.g. as listed on jitpack.io.

We recommend not using SNAPSHOT builds, but a specific commit in a specific branch (like a commit on master), because your build will then be stable.

Build time-out

Have patience when updating the version of fuel or building for the first time as jitpack will build it, and this may cause the request to jitpack to time out. Wait a few minutes and try again (or check the status on jitpack).

NOTE: do not forget to add the kotlinx repository when using coroutines or serialization

Forks

Jitpack.io also allows to build from fuel forks. If a fork's username is $yourname,

• adjust group to com.github.$yourName.fuel
• and look for version on https://jitpack.io/#$yourName/Fuel

Quick start

Fuel requests can be made on the Fuel namespace object, any FuelManager or using one of the String extension methods. If you specify a callback the call is async, if you don't it's blocking.

Async Usage Example

import com.github.kittinunf.fuel.httpGet
import com.github.kittinunf.result.Result;

fun main(args: Array<String>) {

    val httpAsync = "https://httpbin.org/get"
        .httpGet()
        .responseString { request, response, result ->
            when (result) {
                is Result.Failure -> {
                    val ex = result.getException()
                    println(ex)
                }
                is Result.Success -> {
                    val data = result.get()
                    println(data)
                }
            }
        }

    httpAsync.join()
}

Blocking Usage Example

import com.github.kittinunf.fuel.httpGet
import com.github.kittinunf.result.Result;

fun main(args: Array<String>) {

    val (request, response, result) = "https://httpbin.org/get"
        .httpGet()
        .responseString()

    when (result) {
        is Result.Failure -> {
            val ex = result.getException()
            println(ex)
        }
        is Result.Success -> {
            val data = result.get()
            println(data)
        }
    }

}

// You can also use Fuel.get("https://httpbin.org/get").responseString { ... } // You can also use FuelManager.instance.get("...").responseString { ... }

`Fuel` and the extension methods use the `FuelManager.instance` under the hood. You can use this FuelManager to change the default behaviour of all requests:

```kotlin
FuelManager.instance.basePath = "https://httpbin.org"

"/get"
  .httpGet()
  .responseString { request, response, result -> /*...*/ }
// This is a GET request to "https://httpbin.org/get"

Detailed usage

Check each of the packages documentations or the Wiki for more features, usages and examples. Are you looking for basic usage on how to set headers, authentication, request bodies and more? fuel: Basic usage is all you need.

Basic functionality

• fuel: Basic usage
• fuel-android: Android usage
• fuel-coroutines: Execution with coroutines

Responses

• fuel-livedata: Responses as LiveData
• fuel-reactor: Responses as Mono
• fuel-rxjava: Responses as Single

(De)serialization

• fuel-forge: Deserialization with Forge
• fuel-gson: (De)serialization with Gson
• fuel-jackson: Deserialization with Jackson
• fuel-json: Deserialization with Json
• fuel-kotlinx-serialization: (De)serialization with KotlinX Serialization
• fuel-moshi: Deserialization with Moshi

Utility

• fuel-stetho : Debugging bridge for Android with Stetho

Other libraries

If you like Fuel, you might also like other libraries of mine;

• Result - The modelling for success/failure of operations in Kotlin
• Fuse - A simple generic LRU memory/disk cache for Android written in Kotlin
• Forge - Functional style JSON parsing written in Kotlin
• ReactiveAndroid - Reactive events and properties with RxJava for Android SDK

Credits

Fuel is brought to you by contributors.

Licenses

Fuel is released under the MIT license.