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>'

Make sure to include jcenter() in your repositories

repositories {
  jcenter()
}

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://www.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")
}

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 instructionseg. 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:

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

Responses

(De)serialization

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.

Introduction