Definition
Expo is an open-source framework and platform for building cross-platform mobile applications using JavaScript and React Native. It provides developers with tools, libraries, and services to streamline the process of creating, testing, and deploying apps for iOS, Android, and the web from a single codebase. Expo is designed to simplify mobile development by offering pre-built components and managed workflows.
For example, a startup can use Expo to quickly build a mobile app for both iOS and Android without needing deep expertise in native mobile development.
Advanced
Expo offers two primary workflows. The managed workflow allows developers to build apps using Expo’s pre-configured environment without dealing with native code, while the bare workflow provides full control with native modules when needed. Expo includes APIs for camera access, push notifications, sensors, authentication, and offline storage.
Advanced usage involves integrating Expo with CI/CD pipelines, using Over-the-Air (OTA) updates to deliver app changes instantly without resubmitting to app stores, and optimising performance with Expo’s build and bundling services. Developers can also combine Expo with third-party libraries, or eject to native code for deeper customisation. Monitoring tools, performance profiling, and integration with services like Firebase enhance scalability and reliability.
Why it matters
- Simplifies cross-platform app development with one codebase.
- Reduces time to market by removing complex native setup.
- Provides developers with rich APIs and pre-built functionality.
- Enables faster iteration with over-the-air updates.
Use cases
- Building minimum viable products for mobile quickly.
- Deploying apps for iOS and Android without separate development teams.
- Using OTA updates to deliver bug fixes or features instantly.
- Prototyping apps for user testing before full native development.
Metrics
- Build and deployment time for mobile apps.
- App performance benchmarks across platforms.
- User adoption and update rates through OTA deployments.
- Error rates and crash logs tracked in app monitoring tools.
Issues
- Performance limitations compared to fully native development.
- Dependency on Expo’s ecosystem for certain features.
- Restrictions in the managed workflow that require ejecting to native code.
- App size may be larger due to bundled libraries.
Example
An education startup builds a learning app using Expo’s managed workflow. The team delivers iOS and Android versions simultaneously and pushes quick updates through OTA when bugs are found. By avoiding native complexity, the startup reduces development costs and accelerates launch.