Systems Design

React Native

Added: July 16, 2026

Definition

React Native is a framework built on React that lets developers create mobile apps for Android and iOS using JavaScript and React concepts. Instead of rendering HTML in a browser, it renders native mobile UI components like buttons, text fields, and navigation. It sits between your React code and the phone's operating system.

The Problem That Led to It Before React Native, companies usually built two separate apps: one in Swift for iPhone and another in Java/Kotlin for Android. This meant writing and maintaining the same features twice, requiring two teams and increasing development time and cost. Facebook wanted a way to share most of the code while still producing apps that feel native, leading to React Native.

What Problem It Solves

One codebase for Android and iOS.
Faster development and easier maintenance.
Reuses React knowledge for mobile development.
Produces apps that use native UI components.

What Happens If Not Used

You typically maintain separate Android and iOS projects, duplicate business logic, spend more time fixing bugs, and release updates separately.

Easy Wording

React Native lets you build Android and iPhone apps using one React codebase instead of two separate ones.

Layman Example

Imagine writing one instruction manual that works for both a Toyota and a Honda instead of writing two completely different manuals. Each car still uses its own engine, but the instructions are mostly shared.

Technical Example

Before React Native

Developer ↓ Swift Code ──→ iOS App

Developer ↓ Kotlin Code ──→ Android App

Every feature (login, profile, cart) is developed twice.

After React Native

Developer ↓ React Native Code ↓ React Native Bridge / Runtime ↓ Android Native UI iOS Native UI

You implement the login screen once, and React Native translates it into native Android and iOS components while sharing most of the business logic.

Limitation React Native is designed only for mobile apps. It isn't the preferred solution for SEO-friendly websites, server-side rendering, or full-stack web applications. Some platform-specific features may also require writing native code.

Solution

Next.js solves these limitations for the web. It extends React to build production-ready websites with routing, Server-Side Rendering (SSR), Static Site Generation (SSG), API routes, and excellent SEO while keeping the familiar React development model.