# Kotlin and Jetpack Compose

> How larch uses Kotlin and Jetpack Compose: Hiki for Android, a native app on Google Play with the manga marketplace, a store map and push notifications.

URL: https://larch.ee/technologies/kotlin-jetpack-compose/

larch builds native Android apps in Kotlin with Jetpack Compose. Hiki for Android brings the manga marketplace and the store map to phones, with Google sign-in and push notifications, and it is on Google Play.

- Products built: 1
- Language: Kotlin 2.0
- Interface: Compose · Material 3
- Runs on: Android 8.0 and newer
- App languages: EN · RO · RU

## Built with Kotlin and Jetpack Compose

One app, built native. Hiki started on the web. Its Android app is native Kotlin, built by the same team that built the web app and the API behind it.

### [Hiki](https://larch.ee/work/hiki/)

Hiki for Android is Kotlin with about 40 Jetpack Compose screens: the catalog, the marketplace and the store map with your location, plus Google sign-in and push notifications, on the same API as hiki.world.

- Year: 2025
- Stack: Next.js, React, TypeScript, Tailwind CSS, Kotlin, Jetpack Compose, FastAPI, Python, MongoDB, Firebase, Google Cloud
- Live product: https://hiki.world

## Related service

### [Mobile app development](https://larch.ee/services/mobile-app-development/)

Native or cross-platform, built for the way people actually use their phones.

What you get:

- **Native iOS and Android, for peak performance**: Hiki for Android is Kotlin and Jetpack Compose, not a web page in a wrapper.
- **One back end for the web and the app**: The app calls the same FastAPI back end as hiki.world, so the catalog and the marketplace match on every device.
- **Everything from architecture to the store**: Signed release builds, shrunk with R8 and published on Google Play by Stackwise OÜ.

## How we use Kotlin and Jetpack Compose

Native, not wrapped. A manga marketplace with a map has to feel at home on a phone: fast lists, a real map and notifications. So Hiki for Android is native Kotlin from the first screen.

### Hiki: every screen in Compose

Hiki for Android is written in Kotlin 2.0, and every screen is Jetpack Compose with Material 3, themed in the same bold Neubrutalism style as hiki.world. There are no XML layouts. Each screen keeps its state in a ViewModel and exposes it as a StateFlow, so the interface simply follows the data.

### The architecture

Hilt wires the app together through seven modules, one per area: sign-in, lists, the map, the marketplace, the network, notifications and reports. Retrofit with Moshi talks to the hiki.world API, the same FastAPI back end the web app uses, and OkHttp keeps a disk cache, so recent screens still open when the connection drops. Coil loads the covers and the marketplace photos.

### The store map

The store map is Google Maps inside Compose. Markers show the shops, and with your permission the map centres on where you are, so you can find the nearest shop with the volume you want.

### Sign-in and notifications

Sign-in is Google, through Android’s Credential Manager and Firebase Auth, with the same accounts as on the web. Firebase Cloud Messaging delivers the push notifications the back end sends.

### Release

Release builds are signed and shrunk with R8. The app runs on Android 8.0 and newer, in English, Romanian and Russian, and Stackwise OÜ publishes it on Google Play.

## Other technologies

Used alongside it. Hiki for Android signs in with Firebase and talks to a FastAPI back end on Google Cloud. See what else we built with them.

- [Google Cloud and Firebase](https://larch.ee/technologies/google-cloud-firebase/): Hiki’s back end, web app and daily scraper on Cloud Run, and Firebase sign-in for Hiki and Bridddge.
- [Python and FastAPI](https://larch.ee/technologies/python-fastapi/): Hiki’s back end: FastAPI with async MongoDB, the aiohttp scrapers and the pipeline that enriches every title.
- [All technologies](https://larch.ee/technologies/): Eleven technologies, each one running in a product we shipped.

## How to start

Tell us what you want to ship. Bring the idea. We’ll tell you how we’d build it and what it takes.

- Book a 30-minute call: https://calendly.com/nicholas-stackwise/30min
- Email: nicholas@larch.ee