React Native and Expo: mastering cross-platform mobile development

The demand for high-quality mobile applications continues to grow. Maintaining a presence on both iOS and Android at the same time poses a challenge for companies and developers. Instead of maintaining two separate codebases, cross-platform frameworks like React Native and toolkits like Expo offer an efficient alternative. They allow you to write most of the code in JavaScript and run it across multiple platforms without sacrificing performance or user experience. In this article, I present these technologies and explain why they are a smart choice for your mobile projects.

React Native is an open-source framework created by Facebook that lets you build native mobile apps using web technologies, notably JavaScript and React. Unlike classic hybrid approaches, React Native compiles JavaScript code into native components, delivering smooth user experience and performance comparable to what you get with Swift or Kotlin. Its main advantage lies in its architecture: a single codebase can be shared between iOS and Android, dramatically reducing development time and cost. The framework relies on a vast ecosystem of libraries and a very active community, making it easier to integrate complex features like state management, navigation or access to device sensors.

Expo is a suite of tools and services built around React Native that simplifies mobile app development even further. Expo provides a preconfigured environment where you can start a project quickly without having to install Xcode or Android Studio. It offers a set of ready-made APIs and modules for accessing native features such as the camera, GPS, push notifications or in-app purchases. Thanks to its compatibility with iOS and Android, Expo reduces the effort needed to manage platform-specific environments and lets you test your app instantly on your device via the Expo client. One of Expo's strengths is its active community and clear documentation: developers regularly share solutions and tutorials to make the most of the framework.

Key strengths of React Native and Expo:

• Rapid development: hot reload and live reload features let you see changes immediately without recompiling the app, which speeds up development cycles.
• Code sharing: you write the logic once and use it on iOS and Android, reducing the risk of inconsistencies and platform-specific bugs.
• Rich ecosystem: open-source libraries and a component store make it easy to add animations, manage local storage or integrate third-party services.
• Simplified access to native features: Expo provides built-in modules for the camera, accelerometer, media sharing and many others without writing any native code.
• Community and support: the popularity of React Native and Expo's fast-growing adoption ensure responsive support and plenty of documentation.
• Near-native performance: by compiling components to native code, React Native offers performance close to apps written in Swift or Kotlin. Expo, relying on React Native's engine, maintains this level of performance for most use cases.

These solutions do have some limitations you should be aware of:

• Dependency on the Expo platform: when you use Expo in managed mode you depend on the platform's roadmap and updates. Some SDK versions impose delays before accessing new features on iOS or Android.
• Restricted access to native modules: if you need specific features not supported by Expo you will need to switch to the bare workflow or use React Native CLI, which makes setup slightly more complex.
• Application size: using the Expo runtime can increase the final size of the APK or IPA compared to a pure React Native app.
• Learning curve: while React Native is more accessible than native development, you still need to master JavaScript, React and understand the specifics of mobile. Expo adds another layer of tools and configuration you must learn.

The React Native / Expo combination is ideal for projects that require rapid time-to-market, a small team or a proof of concept. If you're developing an internal app for your company, an event app or a prototype that needs to be validated quickly by investors, Expo will help you save time and resources. For complex projects involving deep integration with native modules or specific requirements regarding performance and customisation, you can start with Expo then switch to the bare workflow or use React Native CLI to keep full control. It is important to evaluate the technical requirements and constraints of the project before choosing the most suitable solution.

The success of a mobile application doesn't only depend on choosing a framework. To deliver the best experience you must also focus on ergonomics, optimise performance and follow mobile development best practices. This includes caching data, managing state efficiently, optimising images and resources, and using animations in moderation. Accessibility and compatibility with various devices should be considered from the design stage in order to reach the widest audience. React Native and Expo provide tools to profile your app and detect bottlenecks, helping you deliver a product with professional quality.

In conclusion, React Native and Expo are a powerful combination for developing modern mobile applications. By sharing code and using a well-thought-out toolkit, these technologies allow independent developers like me to deliver robust, scalable products quickly. The ready-made features in Expo, the active community and the ability to switch easily from managed to standalone mode make this solution a major asset for creating cross-platform apps. As a freelance developer specialising in React Native and Expo, I can guide you from design to publication on the app stores, helping to turn your ideas into high-performance apps accessible on all devices.