Technologies / Kotlin
Kotlin app development for modern Android apps
Kotlin app development is our default for native Android: Kotlin for the logic, Jetpack Compose for the UI, coroutines for anything that waits on the network or disk. This page is written for founders and CTOs choosing a stack. It covers why Google moved Android to Kotlin, what coroutines and Kotlin Multiplatform change for your budget, and when Kotlin is the wrong choice.
For scope, process and Play Store launch, see our Android app development services. This page explains the language decision underneath.
- Kotlin and Jetpack Compose by default
- Coroutines and Flow for async work
- Targets current Play API levels
- Code in your own repository
Kotlin-first: what it means for your app
Google has called Android development Kotlin-first since 2019, and UIs built with Jetpack Compose, Android’s recommended UI toolkit, are written in Kotlin (Google’s Kotlin-first page). For a buyer, that settles the language question for new native Android work. Our Java app development page covers the history and how we maintain older Java apps.
Kotlin itself removes whole bug classes common in older Android apps. Null safety is part of the type system, so a value that might be missing has to be handled before the code compiles. Data classes, sealed types and extension functions also cut boilerplate, which means less code to review and maintain.
Coroutines: making async code readable and safe
Many Android bugs that reach production involve timing: a screen rotates while a request is in flight, a user leaves before an upload finishes, two callbacks race to update the same list. Older apps handled this with nested callbacks, AsyncTask or RxJava chains that few people could read.
Kotlin coroutines let developers write asynchronous code that reads top to bottom. Structured concurrency ties each piece of background work to a scope, such as a screen’s ViewModel, so when the user leaves, the work is cancelled instead of leaking memory or writing to a screen that no longer exists. Flow handles streams such as live prices, chat messages or location updates with the same rules.
What we check on every pull request
Work launched in the right scope (viewModelScope or lifecycleScope, never GlobalScope), blocking calls moved to the IO dispatcher, cancellation handled in long loops, and errors caught at the boundary rather than swallowed. These four rules prevent many of the hard-to-reproduce crashes we find in apps we take over.
When we choose Kotlin, and when we do not
We recommend Kotlin app development when Android is your main market or the app depends on the device: background location, Bluetooth, NFC, foreground services, deep integration with specific hardware, or enterprise device management. Android holds 69.2% of worldwide mobile OS share according to StatCounter (September 2026), so markets in South Asia, the Middle East and Africa often justify Android-first.
We do not recommend Kotlin-only when you need iOS and Android at launch on one budget with mostly standard screens. A single cross-platform build in Flutter or React Native is usually cheaper there.
If you are deciding for an existing Java codebase, our Kotlin vs Java for Android comparison covers incremental migration and when Java is still fine.
Choose Kotlin if
- Android is your first or main platform
- You need hardware, background or enterprise device features
- You plan to share logic with iOS via Kotlin Multiplatform
- You are modernising a Java Android app
- You want in-house Android hires later
Kotlin Multiplatform: sharing code with iOS without a full rewrite
Kotlin Multiplatform (KMP) lets a team write business logic once in Kotlin, such as networking, validation, pricing rules and offline sync, and use it from both the Android app and a Swift iOS app. With Compose Multiplatform, the UI can be shared too. JetBrains declared Compose Multiplatform for iOS stable and production-ready in version 1.8.0, May 2025 (JetBrains).
KMP suits teams that already have a strong Kotlin Android app and want iOS without duplicating rules that must match exactly, like loan calculations or booking availability. The trade-off is that your iOS developers consume Kotlin-generated code, and debugging crosses language boundaries. If you are starting from zero on both platforms, compare it with Flutter in our Flutter vs React Native comparison and with two native apps in Swift and Kotlin.
What we build with Kotlin
Typical Kotlin app development work we scope.
Jetpack Compose apps
New native Android apps with Compose UI, Material 3, ViewModels and Kotlin Flow.
Java to Kotlin migration
New features in Kotlin, old classes converted when touched, Views replaced screen by screen.
Shared logic with KMP
A Kotlin module consumed by Android and iOS for rules that must match on both platforms.
Enterprise and field apps
Offline-first data, barcode scanning, background sync and managed-device deployment.
Native modules
Kotlin plugins for Flutter or React Native apps that need an Android API the framework lacks.
Wear OS and TV
Companion apps for watches and Android TV, each with its own layout and input rules.
Planning an Android app?
Send us your feature list. Within one business day you get our view on Kotlin, cross-platform or Kotlin Multiplatform, with the reasons and risks spelled out.
Kotlin compared with the alternatives
How native Kotlin compares with the other ways to ship an Android app.
| Option | Best for | Trade-off |
|---|---|---|
| Kotlin + Jetpack Compose | New Android-first apps and deep device integration | iOS needs a second codebase or KMP |
| Java + Views | Maintaining existing apps only | Against Google’s Kotlin-first, Compose-first direction |
| Kotlin Multiplatform | Sharing business logic with an iOS app | Cross-language debugging; iOS team adapts |
| Flutter (Dart) | iOS and Android from one codebase with custom UI | Platform features need plugins |
| React Native (JS/TS) | Teams with React skills, shared web logic | Native modules for advanced work |
How Kotlin fits your stack, team and maintenance budget
The Kotlin app talks to an API we design with the backend team, typically Node.js, Laravel or Firebase. Delivery tooling is Android Studio, Gradle with version catalogs, Play Console internal testing for every sprint build, and CI on GitHub Actions or Codemagic.
Kotlin is what current Android engineers learn first, so the codebase stays easy to hand over. You can also hire Android developers from us with a two-week trial. Maintenance has a fixed yearly beat: Play target API deadlines fall on 31 August, and from 31 August 2026 new apps and updates must target Android 16 (API level 36), per Google Play’s target API rules. Our maintenance plans schedule that work before the deadline.
Code-quality practices on our Kotlin projects
What you can verify in your own repository.
- Compose UI with state hoisted to ViewModels; no business logic in composables
- Coroutines launched in lifecycle-aware scopes, never GlobalScope
- ktlint or detekt in CI; Android Lint warnings tracked
- Unit tests for ViewModels and use cases; Compose UI tests on critical flows
- Modules split by feature to keep Gradle builds fast
- R8 shrinking with tested keep rules before release
- Crashlytics or Sentry with mapping files uploaded by CI
Kotlin app development: frequently asked questions
Is Kotlin better than Java for Android apps?
For new apps, yes. Google declared Android Kotlin-first in 2019 and Jetpack Compose, the recommended UI toolkit, is Kotlin-only. Kotlin’s null safety and coroutines also prevent common crash types. Java still runs and we maintain Java code in older apps, but starting a new Android project in Java would put you against the platform’s direction and shrink your hiring pool.
Do we need to rewrite our Java Android app?
Rarely. Kotlin and Java interoperate in the same project, so new features go in Kotlin and older classes convert when they are touched for other reasons. Views and Compose can also share a screen during migration. A full rewrite only makes sense when the old code blocks a critical upgrade, and even then we do it module by module.
What is Kotlin Multiplatform and should we use it?
Kotlin Multiplatform shares Kotlin code, usually business logic, between Android and iOS, and Compose Multiplatform can share UI too. It fits teams with a strong Kotlin Android app adding iOS, or apps where rules must match exactly on both platforms. For a new product on both platforms, compare it with Flutter and two native apps before deciding.
Can one Kotlin codebase run on iOS?
Partly. Kotlin Multiplatform compiles shared Kotlin code for iOS, and Compose Multiplatform for iOS has been stable since May 2025. Platform-specific pieces such as payments, push notifications and some permissions still need Swift or platform code. It works well, but plan for some iOS-specific engineering rather than expecting a single codebase to cover everything.
How long does a Kotlin Android app take to build?
It depends on scope. Our MVPs take 8 to 16 weeks after a one-to-two-week discovery, with a demo build in Play internal testing every two-week sprint. Hardware integrations, offline sync and complex admin tooling extend that. A fixed price follows discovery, once the backlog and acceptance criteria are agreed.
What ongoing work does a Kotlin app need?
Every year Google raises the Play target API level, with deadlines on 31 August; apps that miss it stop showing to users on newer Android versions. Add Kotlin, Compose and library upgrades, OS behaviour changes and crash fixes. A maintenance plan keeps this predictable rather than a scramble when the Play Console sends a warning.
Build your Android app on well-structured Kotlin
Book a 30-minute scoping call. We will review your features, any existing Java or Kotlin code, and whether Kotlin Multiplatform makes sense for your iOS plans.