Koasty

Lightweight, customizable toast-style notifications for Compose Multiplatform.

Koasty gives Compose Multiplatform applications a shared notification API across Android, iOS, desktop, and web. Show a short message from common code, let Koasty handle its lifetime and dismissal, and customize the visuals when your product needs a distinct style.

• One Compose API for Android, iOS, JVM desktop, JavaScript, and Wasm.
• Timed, persistent, dismissible, and clickable notifications.
• Swipe-to-dismiss gestures and animated transitions.
• Custom colors, typography, shape, padding, elevation, and animation specs.
• Slots for a leading icon or a completely custom notification layout.
• Direct alert positioning with compact bottom-right defaults on desktop and web.
• No platform UI code required at the call site.

Koasty is configured for publication under:

commonMain.dependencies {
    implementation("io.github.deference3:koasty:0.0.1")
}

If that version has not yet been published to Maven Central, include this repository as a project dependency while developing locally:

// settings.gradle.kts
include(":koasty")

// Your Compose Multiplatform module
kotlin {
    sourceSets {
        commonMain.dependencies {
            implementation(project(":koasty"))
        }
    }
}

Create and remember one KoastManager, then place KoastyProvider around your application content. The provider renders notifications above its content.

import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import com.deference.koasty.KoastManager
import com.deference.koasty.KoastyProvider

@Composable
fun App() {
    val koastManager = remember { KoastManager() }

    KoastyProvider(koastManager = koastManager) {
        Button(
            onClick = {
                koastManager.show(
                    title = "Saved",
                    message = "Your changes are ready."
                )
            }
        ) {
            Text("Show koast")
        }
    }
}

The manager exposes focused methods for common notification behavior:

// Disappears automatically after 3.5 seconds by default.
koastManager.show("Uploaded", "Your image is now available.")

// Custom duration.
koastManager.show(
    title = "Connected",
    duration = 5.seconds //accepts kotlin Duration
)

// Remains until swiped away or dismissed in code.
koastManager.showUntilDismissed(
    title = "You're offline",
    message = "Some features may be unavailable."
)

// Can only be dismissed in code.
koastManager.showPersistent(
    title = "Uploading",
    message = "Please keep the app open."
)

koastManager.dismiss()

Clickable notifications are supported as well:

koastManager.showClickable(
    title = "Update available",
    message = "Tap to view the release notes.",
    onClick = { openReleaseNotes() }
)

Use KoastyHostConfig to adapt the default notification to your design system:

KoastyProvider(
    koastManager = koastManager,
    config = KoastyHostConfig(
        containerColor = MaterialTheme.colorScheme.inverseSurface,
        contentColor = MaterialTheme.colorScheme.inverseOnSurface,
        shape = RoundedCornerShape(16.dp),
        shadowElevation = 12.dp,
        horizontalSwipeEnabled = true,
        swipeUpEnabled = true
    )
) {
    AppContent()
}

You can also provide leading content while retaining Koasty's standard layout and behavior:

KoastyProvider(
    koastManager = koastManager,
    leadingContent = { koast ->
        Text(text = "●")
    }
) {
    AppContent()
}

For complete visual control, pass koastContent and render the current KoastRequest yourself.

Clone the repository and use the included Gradle wrapper:

# Android
./gradlew :androidApp:assembleDebug

# Desktop
./gradlew :desktopApp:run

# Web (Wasm)
./gradlew :webApp:wasmJsBrowserDevelopmentRun

# Web (JavaScript)
./gradlew :webApp:jsBrowserDevelopmentRun

For iOS, open iosApp/iosApp.xcodeproj in Xcode and run the application from there.

On Windows, replace ./gradlew with gradlew.bat.

./gradlew :koasty:build

Native Apple binaries must be built on macOS.

koasty/      Compose Multiplatform library
shared/      Shared UI for the sample applications
androidApp/  Android sample entry point
desktopApp/  Desktop sample entry point
webApp/      JavaScript and Wasm sample entry points
iosApp/      iOS sample entry point

Contributions of all sizes are welcome.

1. Fork the repository and create a branch from main.
2. Keep changes focused and include tests when behavior changes.
3. Run the relevant Gradle build and tests locally.
4. Open a pull request describing the problem and your approach.

For larger API or behavior changes, open an issue first so the design can be discussed before implementation.

Koasty is distributed under the Apache License 2.0. See the repository license for details.

Built with 💖 for Kotlin Multiplatform / Compose Multiplatform .