Cross Platform App Development for Android, iOS and Web

Cross-platform development means building apps for more than one platform, usually Android and iOS, from a shared codebase instead of two separate ones. How much is shared varies by approach: some frameworks share the interface and logic, others share only business logic and keep native interfaces. The goal is to reduce duplicated work while still delivering apps that feel right on each platform.

Key questions guide the decision.

The main options each have a distinct character.

Kotlin Multiplatform lets teams write networking, data storage, business rules and validation once in Kotlin, and use it from both Android and iOS apps. The interface is built natively, with Jetpack Compose on Android and SwiftUI on iOS, or optionally shared using Compose Multiplatform. It suits organisations with strong Android teams, apps with complex shared logic and products where fully native interfaces are a priority. It requires both Android and iOS interface skills.

A progressive web app can be installed from the browser, works offline and can send notifications on supported devices. It suits internal tools, simple ordering or booking apps, content apps and situations where you want to avoid app store processes. It is less suitable when you need app store discovery, advanced device features or the full native experience iPhone users expect. Our PWA development service covers this route.

For the great majority of business and consumer apps, such as ecommerce, booking, fintech, education, healthcare, social and on-demand services, modern cross-platform frameworks deliver smooth, responsive experiences when well engineered. Performance problems usually come from poor implementation rather than the framework. Native development remains preferable for heavy 3D graphics, advanced camera processing, intensive real-time audio or video, and apps that push hardware limits.

Savings depend on how much of the app can be shared and how much platform-specific work is needed. Apps that are mostly screens, forms, lists and API calls share the most. Apps with many native integrations share less. Savings continue after launch, because fixes and new features are built once. We estimate shared and platform-specific effort during the assessment, so you can compare approaches with real numbers rather than general claims.

Even with shared code, some work is platform-specific: store setup, signing and review processes, permission handling and privacy declarations, push notification configuration, payment rules for digital goods, deep links, widgets, background tasks, certain SDK integrations and design adjustments for platform conventions. Planning for these avoids surprises late in the project.

Sometimes. Flutter can build web and desktop apps, React Native can share logic and some UI with React web apps, and Kotlin Multiplatform can share logic with web through Kotlin/JS or WebAssembly. Sharing makes most sense for internal tools and logged-in dashboards. Public marketing websites benefit from a dedicated web framework for speed and search visibility.

We create a shared design system with your colours, typography, components and spacing, then decide deliberately where each platform should differ: navigation and back behaviour, headers, pickers, alerts, sharing and system gestures. Users get a consistent brand and a familiar feel on their own device. Our app UI/UX design team handles this balance.

Yes, and usually gradually. Options include rewriting one module at a time and embedding new shared screens into the existing native apps, sharing business logic first with Kotlin Multiplatform, or planning a full rebuild when both native apps are outdated. We assess the current apps, their users and roadmap to choose the least risky path.

Shared logic is covered by automated unit tests once. Interface and integration tests run on both Android and iOS, and manual testing covers a representative range of devices on both platforms, including budget Android phones and older iPhones. Continuous integration builds and tests both apps on every change.

Android and iOS stores have different review processes and timings. We automate builds and submissions for both, use staged rollouts, and plan releases so features reach both platforms together wherever possible. Feature flags allow features to be switched on simultaneously even if store approvals arrive at different times.

Every framework carries some dependency risk: version upgrades, changes in the ecosystem and third-party packages that stop being maintained. We reduce these risks by choosing mature frameworks with strong backing, limiting dependencies to well-maintained packages, keeping versions current and isolating platform-specific code so it can be replaced if needed. Our app maintenance service handles ongoing upgrades.

These mistakes often lead to disappointing apps.

Good candidates include ecommerce apps, on-demand service apps, booking and appointment apps, education and learning apps, fintech and wallet apps, healthcare apps, loyalty and membership apps, community and social apps, and field and internal business apps. Most of these depend on screens, data and integrations that cross-platform frameworks handle well.

A cross-platform team usually includes developers skilled in the chosen framework, at least one person comfortable with native Android and iOS code for platform-specific work, a designer who understands both platforms, a QA engineer testing on real devices, and a back-end developer. Sharing code does not remove the need for platform knowledge; it concentrates it where it adds the most value.

Every year, Android and iOS release new versions with new requirements, such as target API levels, privacy rules and SDK versions. Cross-platform frameworks typically add support quickly, but apps still need upgrades to the framework and plugins, testing on new OS versions and occasional native adjustments. Planning a regular upgrade cycle avoids last-minute compliance problems before store deadlines.

Costs depend on the chosen approach, number of screens and user roles, design complexity, platform-specific features and native modules, back-end and admin needs, offline and real-time features, web or tablet versions and testing scope. Our app development cost guide compares cross-platform and native cost factors.