Expo

Also called Expo SDK

Part of: React Native Glossary
Also known as: Expo SDK
Related: Expo Router EAS Development Build Continuous Native Generation
Mentioned in: Communication Layer Continuous Native Generation Development Build EAS Expo Router Metro Native Module React Navigation
Updated: September 12, 2026

What is Expo in React Native?

Expo is a framework and toolchain built on React Native. It supplies routing, native modules, build services and updates so teams do not assemble that stack themselves.

The newest JS bundleNative modules in the binaryRuntime key pinsThe console is the native binary, built with EAS Build and released through the stores. Its cards are Expo SDK native modules. The cartridge is the JavaScript bundle: EAS Update ships a new one over the air, and it seats only if its key pins match the binary's runtime fingerprint. Add a native module and the fingerprint changes, so the next update waits at the pawl until a new build re-keys the console.

Expo is a framework built on top of React Native. React Native gives you the renderer and the JavaScript-to-native bridge; Expo adds the parts every app ends up needing — routing, a large library of native modules, build infrastructure, and update delivery.

The React Native documentation now recommends starting new apps with a framework, and Expo is the one it points to. In practice npx create-expo-app is the default entry point for newcomers.

What you get beyond bare React Native:

Expo Router — file-based navigation
The Expo SDK — vetted native modules (expo-camera, expo-notifications, expo-sqlite) that version together
EAS — hosted builds, store submission, and over-the-air updates
Continuous Native Generation — ios/ and android/ folders generated from config rather than hand-maintained

A common misconception is that Expo restricts you to its own APIs. That stopped being true with development builds: any native library works.