Ketoy is a Kotlin-native server-driven UI (SDUI) framework for Android. You write real Jetpack Compose in Kotlin, compile it to a tiny signed .ktx bytecode bundle, and push UI changes over-the-air (OTA) to installed apps in seconds - no Play Store release and no JSON DSL.

How is Ketoy different from JSON-based server-driven UI?

Instead of a JSON schema and a parallel component model, Ketoy uses ordinary Kotlin and Jetpack Compose compiled to Ketoy Bytecode (KBC). Bundles are roughly 20x smaller than equivalent JSON SDUI, Ed25519-signed, and rendered as native Compose on device.

Does Ketoy allow over-the-air (OTA) updates on Android within Play Store policy?

Yes. Ketoy delivers UI and logic changes over-the-air without shipping a new APK/AAB. Bundles execute in a sandbox and render native Compose, which keeps updates within Play Store policies.

What does a developer have to learn to use Ketoy?

Almost nothing new. If it is Jetpack Compose, it is Ketoy. One annotation plus one Gradle task turns an in-APK screen into an OTA-updatable screen. Kotlin, Coroutines, Flow, ViewModel, and Hilt all work as usual.

v0.4Kotlin OTA

Ship Compose UI over the air.

Write real Jetpack Compose. Push updates to every device in seconds.

Get started How it works

CheckoutScreen.kt@KetoyEntryPoint

@KetoyEntryPoint @Composable
fun CheckoutScreen() {
    val vm    = ketoyViewModel<CheckoutViewModel>()
    val state by vm.state.collectAsState()

    Scaffold(topBar = { TopAppBar(title = { Text("Checkout") }) }) { p ->
        LazyColumn(modifier = Modifier.padding(p)) {
            items(state.cartItems) { item ->
                ProductCard(name = item.name, price = item.price)
            }
        }
        Button(onClick = { vm.dispatch("place_order") }) {
            Text("Place Order - $" + state.total)
        }
    }
}
// $ ./gradlew ketoyBundle  →  checkout.ktx  ·  3.4 KB

Ketoy OTA Updates

Ship feature updates over the air.

Push updates straight to devices. Skip the store. Skip the wait.

Aurora

v2.4.1

NEW

Updated over the air · v2.4.1

< 50ms

Load, verify, and parse

< 100ms

First frame, cold

~4KB

A full checkout flow

20×

Smaller than JSON SDUI

Why Ketoy

Update without a release.

Add one annotation. Run one Gradle task. Every device gets the change in seconds.

Instant updates

Fix a bug at 3pm. Every user has it by 3:01. The app never reinstalls.

How it works

Play Store safe

Ketoy generates code on device, the same way ART does. It stays inside Google policy.

Security model

Just Kotlin

It is the Jetpack Compose you already write. Nothing new to learn.

What is supported

What’s supported

If it’s Compose, it’s Ketoy.

Ketoy supports the full Compose toolkit, not a curated subset. When Compose adds a parameter, one command picks it up.

Compose and Material 3

All 35 Material 3 components. Every parameter included.

ScaffoldLazyColumnOutlinedTextFieldButtonTopAppBarAlertDialog+29 more

Language

Plain Kotlin

Data classes, sealed classes, extensions, and lambdas. Real Kotlin, compiled to bytecode.

data classsealedwhenextensionsclosures

Async

Coroutines and Flow

launch, async, withContext, and 9 Flow operators. Structured concurrency included.

launchasyncStateFlowcollectAsStatedebounce

State

ViewModel

A real Android ViewModel. It survives config changes and works with Hilt.

viewModelScopeSavedStateHandle@HiltViewModeldispatch()

I/O

Networking and storage

HTTP, DataStore, Room, and navigation. 67 capabilities built in.

HTTPDataStoreRoomNavController+ your SDKs

Hilt

Drop it in. @Inject works exactly as before.

@Inject@HiltViewModel@Moduledev overlay

One annotation and one Gradle task. That is the whole difference.

See everything Ketoy supports

Security

Secure and compliant.

Ketoy verifies every bundle before it runs. Here is how, in three parts.

Every bundle is signed

An Ed25519 signature is checked before any code runs. Your private key stays on your server. Only you can ship a bundle.

The sandbox is a build error

The compiler rejects file access, reflection, and any unregistered API. Unsafe code never compiles.

Capabilities are the only door

KBC code reaches the platform through registered capabilities. Nothing else is callable.

Is this allowed on the Play Store?

Yes. Ketoy generates code on device, exactly like ART does with bytecode. It is the same idea as Lua in a game engine. If your CDN goes down, the last signed bundle keeps running.

Quick start

Three blocks. One Gradle task.

Add the plugin. Write your Compose screen. Run ketoyBundle and upload.

build.gradle.kts

plugins {
  id("dev.ketoy.compiler") version "0.4.13-alpha"
}

dependencies {
  implementation(platform("dev.ketoy.vm:ketoy-bom:0.4.13-alpha"))
  implementation("dev.ketoy.vm:ketoy-runtime")
  implementation("dev.ketoy.vm:ketoy-hilt")
  implementation("dev.ketoy.vm:ketoy-adapters-material3")
  ksp("dev.ketoy.vm:ketoy-ksp-processor")
}

HomeScreen.kt

// The same Compose you already write.
@KetoyEntryPoint
@Composable
fun HomeScreen() {
  val vm    = ketoyViewModel<HomeViewModel>()
  val state by vm.state.collectAsState()

  Column(modifier = Modifier.fillMaxSize().padding(16.dp)) {
    Text("Welcome, " + state["name"])
    Button(onClick = { vm.dispatch("get_started") }) {
      Text("Get Started")
    }
  }
}

terminal~60s rollout

# Compile to KBC
$ ./gradlew :ketoy-screens:ketoyBundle

> Task :ketoy-screens:ketoyBundle
  HomeScreen.kt        → home.ktx        2.1 KB
  CheckoutScreen.kt    → checkout.ktx    3.4 KB
  Signed:    Ed25519
  Compressed:Brotli q=11

# Upload. That's the whole release process.
$ aws s3 cp build/ketoy-bundles/ s3://cdn/ketoy/ \
    --recursive --content-encoding br

# Live on every device in ~60s.

Stuck on something, evaluating Ketoy for your team, or wondering if your weird in-house SDK is supported? We answer every email. Usually within the same day. Sometimes faster than your Play Store review.