> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/expo/expo/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction to Development Builds

> Learn about development builds and when to use them instead of Expo Go.

Development builds are custom versions of the Expo Go app that include your app's native code and third-party libraries. They provide a development environment closer to your production app while maintaining fast iteration speeds.

## What are Development Builds?

A development build is a debug build of your app that includes the `expo-dev-client` package. Unlike Expo Go, which has a fixed set of native modules, development builds contain exactly the native code your app needs.

Development builds include:

* **Custom native modules** - Any native module from npm or your own native code
* **Dev client UI** - A launcher screen to load different versions of your JavaScript
* **Enhanced debugging** - Improved network inspection, error boundaries, and developer menu
* **Fast iteration** - Hot reloading and fast refresh for JavaScript changes

## Expo Go vs Development Builds

<table>
  <thead>
    <tr>
      <th>Feature</th>
      <th>Expo Go</th>
      <th>Development Build</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td>Native modules</td>
      <td>Fixed set included</td>
      <td>Any module you install</td>
    </tr>

    <tr>
      <td>Setup time</td>
      <td>Instant (just download)</td>
      <td>Requires initial build (\~10-20 min)</td>
    </tr>

    <tr>
      <td>JS iteration</td>
      <td>Instant reload</td>
      <td>Instant reload</td>
    </tr>

    <tr>
      <td>Native changes</td>
      <td>Not possible</td>
      <td>Requires rebuild</td>
    </tr>

    <tr>
      <td>Production-like</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
  </tbody>
</table>

## When to Use Development Builds

You should use development builds when:

### 1. Using Custom Native Modules

If your app requires native modules not included in Expo Go:

```json title="app.json" theme={null}
{
  "expo": {
    "plugins": [
      "expo-camera",
      "expo-media-library",
      ["expo-build-properties", {
        "android": { "minSdkVersion": 24 }
      }]
    ]
  }
}
```

### 2. Testing Native Configuration

When you need to test platform-specific settings:

* iOS entitlements and capabilities
* Android permissions and manifest configurations
* Custom app icons, splash screens, or schemes
* Native build properties (SDK versions, architectures)

### 3. Preparing for Production

Development builds use the same native code as production:

```bash theme={null}
# Same native code for development and production
npx expo run:ios --configuration Release
npx expo run:android --variant release
```

### 4. Working in Teams

Share builds with teammates without Xcode or Android Studio:

* iOS: Distribute via TestFlight or ad-hoc provisioning
* Android: Share APK files directly

## Benefits

### Faster Development Workflow

Once the initial build is complete, you get:

* Instant JavaScript reloads
* No need to rebuild for JS changes
* Hot module replacement
* Fast refresh

### Production Parity

Your development environment matches production:

* Same native dependencies
* Same build configuration
* Same bundling process
* Same performance characteristics

### Enhanced Developer Experience

`expo-dev-client` adds powerful tools:

```typescript theme={null}
import { useDevToolsPluginClient } from 'expo/devtools';

export function MyComponent() {
  const client = useDevToolsPluginClient('my-plugin');
  
  // Enhanced debugging capabilities
  client?.sendMessage('debug', { data: 'test' });
}
```

### Flexible Deployment Options

* Test multiple JavaScript bundles without rebuilding
* Load PR previews instantly
* Switch between development servers
* Test updates and rollbacks

## Development Build Workflow

A typical development workflow:

<Steps>
  <Step title="Install expo-dev-client">
    ```bash theme={null}
    npx expo install expo-dev-client
    ```
  </Step>

  <Step title="Create a development build">
    ```bash theme={null}
    # Local build
    npx expo run:ios
    npx expo run:android

    # Or cloud build with EAS
    eas build --profile development --platform ios
    ```
  </Step>

  <Step title="Start the dev server">
    ```bash theme={null}
    npx expo start --dev-client
    ```
  </Step>

  <Step title="Iterate on JavaScript">
    Make changes to your JavaScript code - they reload instantly.
  </Step>

  <Step title="Rebuild when needed">
    Only rebuild when you:

    * Install new native modules
    * Change native configuration
    * Update `app.json` plugins
  </Step>
</Steps>

## Cost Considerations

### Local Builds (Free)

* Build on your own machine
* Requires Xcode (iOS) or Android Studio (Android)
* Full control over build environment

### EAS Build (Paid)

* Cloud building service
* No local tooling required
* Faster builds on powerful servers
* Free tier available

## Next Steps

<CardGroup cols={2}>
  <Card title="Creating Builds" icon="hammer" href="/development/creating-builds">
    Learn how to create your first development build
  </Card>

  <Card title="Installation" icon="mobile" href="/development/installation">
    Install builds on your devices
  </Card>

  <Card title="Debugging" icon="bug" href="/development/debugging">
    Debug your development builds
  </Card>

  <Card title="Testing" icon="flask" href="/development/unit-testing">
    Set up testing for your app
  </Card>
</CardGroup>