Project Url: orbit-mvi/orbit-mvi
Introduction: A simple MVI framework for Kotlin Multiplatform and Android
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What is Orbit

Orbit is a Redux/MVI-like library - but without the baggage. It's so simple we think of it as MVVM+.

  • Simple, type-safe, coroutine-style, extensible API
  • Multiplatform, targetting Android and iOS (iOS support is in alpha and being actively worked on)
  • Full support for Kotlin Coroutines (it's built on top of them after all)
  • Lifecycle-safe collection of infinite flows
  • ViewModel support, along with SavedState
  • Optional, simple unit test library
  • Built-in espresso idling resource support
  • Compatible with RxJava, LiveData etc. through coroutine wrappers
  • And more...


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Getting started


// or, if on Android:
// If using Jetpack Compose include

// Tests

Define the contract

data class CalculatorState(
    val total: Int = 0

sealed class CalculatorSideEffect {
    data class Toast(val text: String) : CalculatorSideEffect()

Create the ViewModel

  1. Implement the ContainerHost interface
  2. Override the container field and use the ViewModel.container factory function to build an Orbit Container in your ContainerHost
class CalculatorViewModel: ContainerHost<CalculatorState, CalculatorSideEffect>, ViewModel() {

    // Include `orbit-viewmodel` for the factory function
    override val container = container<CalculatorState, CalculatorSideEffect>(CalculatorState())

    fun add(number: Int) = intent {
        postSideEffect(CalculatorSideEffect.Toast("Adding $number to ${state.total}!"))

        reduce {
            state.copy(total = state.total + number)

We have used an Android ViewModel as the most common example, but there is no requirement to do so.

Connect to the ViewModel in your Activity or Fragment

class CalculatorActivity: AppCompatActivity() {

    // Example of injection using koin, your DI system might differ
    private val viewModel by viewModel<CalculatorViewModel>()

    override fun onCreate(savedState: Bundle?) {

        addButton.setOnClickListener { viewModel.add(1234) }

        viewModel.observe(state = ::render, sideEffect = ::handleSideEffect)

    private fun render(state: CalculatorState) {

    private fun handleSideEffect(sideEffect: CalculatorSideEffect) {
        when (sideEffect) {
            is CalculatorSideEffect.Toast -> toast(sideEffect.text)

With Jetpack Compose wire up the ViewModel as follows:

fun CalculatorScreen(viewModel: CalculatorViewModel) {

    val state = viewModel.collectAsState().value

    viewModel.collectSideEffect { handleSideEffect(it) }

    // render UI using data from 'state'

private fun handleSideEffect(sideEffect: CalculatorSideEffect) {
    when (sideEffect) {
        is CalculatorSideEffect.Toast -> toast(sideEffect.text)


Please read contributing for details on our code of conduct, and the process for submitting pull requests to us.


We use SemVer for versioning. For the versions available, see the tags on this repository.



This project is licensed under the Apache License, Version 2.0 - see the license file for details

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