This project is named after the Kaluga, the world's biggest freshwater fish, which is found in the icy Amur river.

Kaluga's main goal is to provide access to common features used in cross-platform application development, separated into modules such as location, permissions, bluetooth etc.

To reach this goal it uses Kotlin, specifically Kotlin Multiplatform, recommended in combination with Compose Multiplatform. Supported targets differ per module depending on platform features. We aim to support Android, iOS/iPadOS, macOS, watchOS, tvOS, Javascript, and Javascript WebAssembly where applicable.

Where appropriate coroutines and Flow are used in the API. This enables developers to use cold streams for a modern and efficient design.

While Kaluga modules can be used individually, together they form a comprehensive approach to cross-platform development.

Short examples

With Kaluga it is possible to create cross-platform functionality in a few lines of code, that would normally take many lines of code even on just one platform.

Below are some examples, using a commonMain source-set:

Localization:

val locale = KalugaLocale.defaultLocale
val casing = "istanbul".upperCased(locale) // locale-aware, e.g. "İSTANBUL" in tr
if (locale.unitSystem == UnitSystem.IMPERIAL) i("this locale prefers imperial units")

DateTime:

val tomorrow = DefaultKalugaDate.now().apply { day += 1 }
val formatter = KalugaDateFormatter.dateFormat(DateFormatStyle.Medium)
i(formatter.format(tomorrow)) // e.g. "Jul 8, 2026"

Observing location:

val locationStateRepo = LocationStateRepoBuilder().create(Permissions.Location(background=false, precise=true))
locationStateRepo.location().collect { location ->
    // Handle location change
}

Scanning for nearby devices with Bluetooth LE:

// will auto request permissions and try to enable bluetooth
val client = BluetoothClientBuilder().createClient()
client.startScanning()    
try {
    client.devices().collect {
        i("discovered device: $it") // log found device
    }
} finally {
    client.stopScanning()
}

Scientific calculations:

val forceInNewton = 60(Kilogram) * 4(Meter per Second per Second)
val forceInPoundForce = forceInNewton.convert(PoundForce)
i("${CommonScientificValueFormatter.default.format(forceInNewton)} == ${CommonScientificValueFormatter.default.format(forceInPoundForce)}")

More examples

Kaluga contains an example project that is used to test the developed modules. A Javascript version of this example can be found on https://kaluga.splendo.com/example/

Using Kaluga

Kaluga is available on Maven Central. For example the Kaluga Alerts can be imported like this:

repositories {
    mavenCentral()
}
dependencies {
    implementation("com.splendo.kaluga.alerts:alerts:$kalugaVersion")
}

You can also use the SNAPSHOT version based on the latest in the develop branch:

repositories {
    maven("https://s01.oss.sonatype.org/content/repositories/snapshots/")
}
dependencies {
    implementation("com.splendo.kaluga.alerts:alerts:$kalugaDevelopVersion-SNAPSHOT")
}

Available Modules

Modules are organized into feature groups; each group directory has its own README with more detail. The table below lists every published module, its artifact coordinate, and the platforms it supports.

Module	Usage	Artifact	Android	iOS	JVM	JS	WasmJS	macOS	tvOS	watchOS
alerts/alerts	Showing alert dialogs	com.splendo.kaluga.alerts:alerts	✅	✅
alerts/test-utils	Test helpers for the alerts module	com.splendo.kaluga.alerts:test	✅	✅
architecture/architecture	MVVM architecture	com.splendo.kaluga.architecture:architecture	✅	✅
architecture/compose	Compose extensions for architecture	com.splendo.kaluga.architecture:compose	✅
architecture/test-utils	Test helpers for the architecture module	com.splendo.kaluga.architecture:test	✅	✅
architecture/test-koin	Koin-based test helpers	com.splendo.kaluga.architecture:test-koin	✅	✅
base/core	Threading, flowables and concurrent collections	com.splendo.kaluga.base:core	✅	✅	✅	✅	✅	✅	✅	✅
base/state	State machines (KalugaState, StateRepo)	com.splendo.kaluga.base:state	✅	✅	✅	✅	✅	✅	✅	✅
base/decimal	High-precision decimal arithmetic	com.splendo.kaluga.base:decimal	✅	✅	✅	✅	✅	✅	✅	✅
base/bytes	ByteArray utilities, hex conversion and numeric byte encoding	com.splendo.kaluga.base:bytes	✅	✅	✅	✅	✅	✅	✅	✅
base/crc	Cyclic Redundancy Check (CRC) calculation	com.splendo.kaluga.base:crc	✅	✅	✅	✅	✅	✅	✅	✅
base/i18n	Locales, unit systems and locale-aware String casing	com.splendo.kaluga.base:i18n	✅	✅	✅	✅	✅	✅	✅	✅
base/formatting	Formatting and parsing of numbers and strings	com.splendo.kaluga.base:formatting	✅	✅	✅	✅	✅	✅	✅	✅
base/test-utils	Test helpers built on top of base	com.splendo.kaluga.base:test	✅	✅	✅	✅	✅	✅	✅	✅
bluetooth/core	Shared Bluetooth attributes and the BluetoothFormat (de)serialization framework	com.splendo.kaluga.bluetooth:core	✅	✅		✅	✅	✅	✅	✅
bluetooth/client	Scanning for and connecting to BLE devices as a Client	com.splendo.kaluga.bluetooth:client	✅	✅		✅	✅	✅	✅	✅
bluetooth/server	Advertising and exposing GATT attributes as a Server	com.splendo.kaluga.bluetooth:server	✅	✅				✅
bluetooth/beacons	Tracking the availability of Beacons using the Eddystone protocol	com.splendo.kaluga.bluetooth:beacons	✅	✅				✅	✅	✅
bluetooth/test-utils/core	Test helpers for the Bluetooth core module	com.splendo.kaluga.bluetooth:test-core	✅	✅		✅	✅	✅	✅	✅
bluetooth/test-utils/client	Test helpers for the Bluetooth client module	com.splendo.kaluga.bluetooth:test-client	✅	✅		✅	✅	✅	✅	✅
bluetooth/test-utils/server	Test helpers for the Bluetooth server module	com.splendo.kaluga.bluetooth:test-server	✅	✅				✅
date-time/date-time	Dates, time zones and date formatting	com.splendo.kaluga.date-time:date-time	✅	✅	✅	✅	✅	✅	✅	✅
date-time/timer	A RecurringTimer providing ticks at regular intervals	com.splendo.kaluga.date-time:timer	✅	✅	✅	✅	✅	✅	✅	✅
date-time-picker/date-time-picker	Showing a Date or Time Picker	com.splendo.kaluga.date-time-picker:date-time-picker	✅	✅
date-time-picker/test-utils	Test helpers for the Date Time Picker module	com.splendo.kaluga.date-time-picker:test	✅	✅
hud/hud	Showing a loading-indicator HUD	com.splendo.kaluga.hud:hud	✅	✅
hud/test-utils	Test helpers for the HUD module	com.splendo.kaluga.hud:test	✅	✅
keyboard/keyboard	Showing and hiding the keyboard	com.splendo.kaluga.keyboard:keyboard	✅	✅
keyboard/compose	Compose extensions for keyboard	com.splendo.kaluga.keyboard:compose	✅
keyboard/test-utils	Test helpers for the keyboard module	com.splendo.kaluga.keyboard:test	✅	✅
lifecycle/lifecycle	Platform-host lifecycle bindings for service builders	com.splendo.kaluga.lifecycle:lifecycle	✅	✅	✅	✅	✅	✅	✅	✅
lifecycle/compose	Compose extensions for lifecycle	com.splendo.kaluga.lifecycle:compose	✅	✅			✅	✅
lifecycle/test-utils	Test helpers for the lifecycle module	com.splendo.kaluga.lifecycle:test	✅	✅	✅	✅	✅	✅	✅	✅
links	Decoding a url into an object	com.splendo.kaluga:links	✅	✅		✅	✅	✅	✅	✅
location/location	Provides the user's geolocation	com.splendo.kaluga.location:location	✅	✅		✅	✅	✅	✅	✅
location/test-utils	Test helpers for the location module	com.splendo.kaluga.location:test	✅	✅		✅	✅	✅	✅	✅
logging	Shared console logging	com.splendo.kaluga:logging	✅	✅	✅	✅	✅	✅	✅	✅
media/media	Playing audio/video	com.splendo.kaluga.media:media	✅	✅		✅	✅	✅	✅
media/compose	Compose extensions for media	com.splendo.kaluga.media:compose	✅	✅			✅	✅
media/test-utils	Test helpers for the media module	com.splendo.kaluga.media:test	✅	✅		✅	✅	✅	✅
permissions/core	The permissions framework, used in conjunction with the per-type modules	com.splendo.kaluga.permissions:core	✅	✅		✅	✅	✅	✅	✅
permissions/bluetooth	Managing Bluetooth permissions	com.splendo.kaluga.permissions:bluetooth	✅	✅		✅	✅	✅	✅	✅
permissions/calendar	Managing calendar permissions	com.splendo.kaluga.permissions:calendar	✅	✅				✅		✅
permissions/camera	Managing camera permissions	com.splendo.kaluga.permissions:camera	✅	✅		✅	✅	✅
permissions/contacts	Managing contacts permissions	com.splendo.kaluga.permissions:contacts	✅	✅				✅		✅
permissions/location	Managing location permissions	com.splendo.kaluga.permissions:location	✅	✅		✅	✅	✅	✅	✅
permissions/microphone	Managing microphone permissions	com.splendo.kaluga.permissions:microphone	✅	✅		✅	✅	✅	✅	✅
permissions/notifications	Managing notifications permissions	com.splendo.kaluga.permissions:notifications	✅	✅		✅	✅	✅	✅	✅
permissions/storage	Managing storage permissions	com.splendo.kaluga.permissions:storage	✅	✅				✅	✅
permissions/test-utils	Test helpers for the Permissions modules	com.splendo.kaluga.permissions:test	✅	✅		✅	✅	✅	✅	✅
resources/resources	Shared Strings, Images, Colors and Fonts	com.splendo.kaluga.resources:resources	✅	✅
resources/compose	Compose extensions for resources	com.splendo.kaluga.resources:compose	✅
resources/databinding	Data Binding extensions for resources	com.splendo.kaluga.resources:databinding	✅
resources/test-utils	Test helpers for the resources module	com.splendo.kaluga.resources:test	✅	✅
review	Requesting the user to review the app	com.splendo.kaluga:review	✅	✅				✅
scientific/scientific	Scientific units and conversions	com.splendo.kaluga.scientific:scientific	✅	✅	✅	✅	✅	✅	✅	✅
scientific/converters	Converters between scientific units	com.splendo.kaluga.scientific:converters	✅	✅	✅	✅	✅	✅	✅	✅
service/service	Adding services to Kaluga	com.splendo.kaluga.service:service	✅	✅	✅	✅	✅	✅	✅	✅
service/test-utils	Test helpers for the service module	com.splendo.kaluga.service:test	✅	✅	✅	✅	✅	✅	✅	✅
system/system	System APIs such as network, audio, battery	com.splendo.kaluga.system:system	✅	✅		✅	✅	✅
system/test-utils	Test helpers for the system module	com.splendo.kaluga.system:test	✅	✅		✅	✅	✅

Friends of kaluga

Of course not every possible functionality is provided by kaluga. However, this is often because other good multiplatform libraries that work nicely with kaluga already exist. These use similar patterns such as coroutines and Flow, and include the following:

Project	Usage
kotlin-firebase-sdk	wraps most of the Firebase SDK APIs
multiplatform-settings	store key/value data
SQLDelight	access SQLite (and other SQL database)

Kaluga also uses some multiplatform libraries itself, so our thanks to:

Project	Usage
Napier	powers the logging module
Koin	dependency injection

Developing Kaluga

see DEVELOP.