1--- 2title: Expo CLI 3maxHeadingDepth: 4 4description: The Expo CLI is a command-line tool that is the primary interface between a developer and other Expo tools. 5--- 6 7import { Terminal } from '~/ui/components/Snippet'; 8import { StatusTag } from '~/ui/components/Tag'; 9 10> **info** This documentation refers to the Local Expo CLI (SDK 46 and above). For information on legacy Expo CLI, see [Global Expo CLI](/archive/expo-cli). 11 12The `expo` package provides a small and powerful CLI tool `npx expo` which is designed to keep you moving fast during app development. 13 14## Highlights 15 16- [Start a server](#develop) for developing your app: `npx expo start`. 17- [Generate the native iOS and Android directories](#prebuild) for your project: `npx expo prebuild`. 18- [Build and run](#compiling) the native apps locally: `npx expo run:ios` and `npx expo run:android`. 19- [Install and update packages](#install) that work with the version of `react-native` in your project: `npx expo install package-name`. 20- `npx expo` can be used with `npx react-native` simultaneously. 21 22To view a list of available commands in Expo CLI, run the following in your project: 23 24<Terminal cmd={['$ npx expo -h']} /> 25 26> You can also run `yarn expo -h` if you prefer to use yarn as the package manager. 27 28The output should look something like below: 29 30```shell 31Usage 32 $ npx expo <command> 33 34Commands 35 start, export, export:web 36 run:ios, run:android, prebuild 37 install, customize, config 38 login, logout, whoami, register 39 40Options 41 --version, -v Version number 42 --help, -h Usage info 43``` 44 45You can run any command with the `--help` or `-h` flag to learn more about it: 46 47<Terminal cmd={['$ npx expo login -h']} /> 48 49## Installation 50 51Expo CLI is included in the `expo` package. You can install it with npm or yarn: 52 53<Terminal cmd={['$ yarn add expo']} /> 54 55> Projects that are not using [Expo Prebuild](#prebuild) (often referred to as _Bare workflow_) will need to perform additional setup to ensure all custom Expo bundling features work: [Metro: Bare workflow setup](/versions/latest/config/metro#bare-workflow-setup). 56 57## Develop 58 59Start a development server to work on your project by running: 60 61<Terminal cmd={['$ npx expo start']} /> 62 63> You can also run `npx expo` as an alias to `npx expo start`. 64 65This command starts a server on `http://localhost:8081` (for SDK 48 and lower, the port number is `19000`) that a client can use to interact with the bundler. The default bundler is [Metro](https://facebook.github.io/metro/). 66 67The UI that shows up in the process is referred to as the **Terminal UI**. It contains a QR code (for the dev server URL) and a list of keyboard shortcuts you can press: 68 69| Keyboard shortcut | Description | 70| ------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | 71| <kbd>A</kbd> | Open the project on a connected Android device. | 72| <kbd>Shift</kbd> + <kbd>A</kbd> | Select an Android device or emulator to open. | 73| <kbd>I</kbd> | Open the project in an iOS simulator. | 74| <kbd>Shift</kbd> + <kbd>I</kbd> | Select an iOS Simulator to open. | 75| <kbd>W</kbd> | Open the project in a web browser. This may require webpack to be installed in your project. | 76| <kbd>R</kbd> | Reload the app on any connected device. | 77| <kbd>S</kbd> | Switch the launch target between Expo Go and development builds. | 78| <kbd>M</kbd> | Open the dev menu on any connected native device (web not supported). | 79| <kbd>Shift</kbd> + <kbd>M</kbd> | Choose more commands to trigger on connected devices.<br/>This includes toggling the performance monitor, opening the element inspector, reloading the device, and opening the dev menu. | 80| <kbd>J</kbd> | Open Chrome Dev Tools for any connected device that is using Hermes as the JavaScript engine. [Learn more](/guides/using-hermes#javascript-inspector-for-hermes). | 81| <kbd>O</kbd> | Open project code in your editor. This can be configured with the `EXPO_EDITOR` and `EDITOR` [environment variables](#environment-variables). | 82| <kbd>E</kbd> | Show the development server URL as a QR code in the terminal. | 83| <kbd>?</kbd> | Show all Terminal UI commands. | 84 85### Launch target 86 87The `npx expo start` command automatically launches the app in a development build if `expo-dev-client` is installed in the project. Otherwise, it launches the app in Expo Go. 88 89Alternatively, you can force the launch target by passing the following flags to the command: 90 91- `--dev-client`: Always launch the app in a development build. 92- `--go`: Always launch the app in Expo Go. 93 94You can also switch the launch target during runtime by pressing <kbd>S</kbd> in the **Terminal UI**. The `run` commands also use `--dev-client` after compiling the development build, by default. 95 96### Server URL 97 98By default, the project is served over a LAN connection. You can change this behavior to localhost-only by using the flag `npx expo start --localhost`. 99 100Other available options are: 101 102- `--port`: Port to start the dev server on (does not apply to webpack or [tunnel URLs](#tunneling)). Default: **8081**. For SDK 48 and lower, defaults to `19000`. 103- `--https`: Start the dev server using a secure origin. This is currently only supported on web. 104 105You can force the URL to be any value with the `EXPO_PACKAGER_PROXY_URL` environment variable. For example: 106 107<Terminal cmd={['$ export EXPO_PACKAGER_PROXY_URL=http://expo.dev', '$ npx expo start']} /> 108 109Will open apps to: `exp://expo.dev:80` (the `:80` is a temporary workaround for Android WebSockets). 110 111#### Tunneling 112 113Restrictive network conditions (common for public Wi-Fi), firewalls (common for Windows users), or Emulator misconfiguration can make it difficult to connect a remote device to your dev server over lan/localhost. 114 115Sometimes it's easier to connect to a dev server over a proxy URL that's accessible from any device with internet access, this is referred to as **tunneling**. `npx expo start` provides built-in support for **tunneling** via [ngrok][ngrok]. 116 117To enable tunneling, first install `@expo/ngrok`: 118 119<Terminal cmd={['$ npm i -g @expo/ngrok']} /> 120 121Then run the following to start your dev server from a _tunnel_ URL: 122 123<Terminal cmd={['$ npx expo start --tunnel']} /> 124 125This will serve your app from a public URL like: `http://xxxxxxx.bacon.19000.exp.direct:80`. 126 127**Drawbacks** 128 129- Tunneling is slower than local connections because requests must be forwarded to a public URL. 130- Tunnel URLs are public and can be accessed by any device with a network connection. Expo CLI mitigates the risk of exposure by adding entropy to the beginning of the URL. Entropy can be reset by clearing the `.expo` directory in your project. 131- Tunnels require a network connection on both devices, meaning this feature cannot be used with the `--offline` flag. 132 133#### Offline 134 135You can develop without a network connection by using the `--offline` flag: 136 137<Terminal cmd={['$ npx expo start --offline']} /> 138 139Offline will prevent the CLI from making network requests. If you don't use the flag and your computer has no internet connection, then offline support will automatically be enabled, it will just take a bit longer to verify the reachability. 140 141Expo CLI makes network requests to sign manifests with your user credentials to ensure sensitive information is sandboxed in reusable runtimes like Expo Go. 142 143### .expo directory 144 145When you start the development server in a project for the first time, a **.expo** directory is created at the root of that project. It contains two files: 146 147- **devices.json**: Contains information about devices that have opened this project recently. 148- **settings.json**: Contains information about server configuration that is used to serve the project's manifest. 149 150Both of these files have information that is specific to your local computer. This is the reason why **.expo** directory is included in the **.gitignore** file, by default, when a new project is created. It is not meant to be shared with other developers. 151 152## Building 153 154A React Native app consists of two parts: a native runtime ([compiling](#compiling)), and static files like JavaScript bundles and assets ([exporting](#exporting)). Expo CLI provides commands for performing both tasks. 155 156### Compiling 157 158You can compile your app locally with the `run` commands: 159 160<Terminal 161 cmd={['# Build for iOS', '$ npx expo run:ios', '# Build for Android', '$ npx expo run:android']} 162/> 163 164**Highlights** 165 166- Build directly on connected devices with no global side effects using the `--device` flag. Supports locked devices, letting you retry instantly instead of needing to rebuild. 167- Automatically codesign iOS apps for development from the CLI without having to open Xcode. 168- Smart log parsing shows warnings and errors from your project source code, unlike Xcode which surfaces hundreds of benign warnings from your node modules. 169- Fatal errors causing your app to crash will be surfaced in the terminal preventing the need to reproduce in Xcode. 170 171`npx expo run:ios` can only be run on a Mac, and Xcode must be installed. You can build the app in the cloud from any computer using `eas build -p ios`. Similarly, `npx expo run:android` requires Android Studio and Java to be installed and configured on your computer. 172 173Building locally is useful for developing native modules and [debugging complex native issues](/debugging/runtime-issues/#native-debugging). Building remotely with `eas build` is a much more resilient option due to the pre-configured cloud environment. 174 175If your project does not have the corresponding native directories, the `npx expo prebuild` command will run once to generate the respective directory before building. 176 177For example, if your project does not have an **ios** directory in the root of your project, then `npx expo run:ios` will first run `npx expo prebuild -p ios` before compiling your app. For more information on this process, see [Expo Prebuild](/workflow/prebuild). 178 179**Cross-Platform Arguments** 180 181- `--no-build-cache`: Clear the native cache before building. On iOS, this is the **derived data** folder. Cache clearing is useful for profiling your build times. 182- `--no-install`: Skip installing dependencies. On iOS, this will also skip running `npx pod-install` if the `dependencies` field in the project's `package.json` has changed. 183- `--no-bundler`: Skip starting the dev server. Enabled automatically if the dev server is already serving the app from a different process. 184- `-d, --device [device]`: Device name or ID to build the app on. You can pass `--device` without arguments to select a device from a list of available options. This supports connected devices as well as virtual devices. 185- `-p, --port <port>`: Port to start the development server. **Default: 8081**. This is only relevant for development builds. Production builds will [export](#exporting) the project and embeds the files in the native binary before installing them on a device. 186 187#### Compiling Android 188 189Android apps can have multiple different **variants** which are defined in the project's `build.gradle` file. Variants can be selected with the `--variant` flag: 190 191<Terminal cmd={['$ npx expo run:android --variant debug']} /> 192 193You can compile the Android app for production by running: 194 195<Terminal cmd={['$ npx expo run:android --variant release']} /> 196 197This build is not automatically code-signed for submission to the Google Play Store. This command should be used to test bugs that may only show up in production builds. To generate a production build that is code signed for the Play Store, we recommend using [EAS Build](/build/introduction). 198 199You can debug the native Android project using native debugging tools by opening the `android/` folder in Android Studio: 200 201<Terminal cmd={['$ open -a /Applications/Android Studio.app android']} /> 202 203#### Compiling iOS 204 205An iOS app can have multiple **schemes** for representing different sub-apps like App Clips, watchOS apps, Safari Extensions, and so on. By default, `npx expo run:ios` will choose the scheme for your iOS app. You can pick a custom scheme with the `--scheme <my-scheme>` argument. If you pass in the `--scheme` argument alone, then Expo CLI will prompt you to choose a scheme from the list of available options in your Xcode project. 206 207The scheme you select will filter out which `--device` options show up in the selection prompt, for example, selecting an Apple TV scheme will only show available Apple TV devices. 208 209You can compile an iOS app for production by running: 210 211<Terminal cmd={['$ npx expo run:ios --configuration Release']} /> 212 213This build is not automatically code signed for submission to the Apple App Store. `npx expo run:ios` should mostly be used to test bugs that only show up in production builds. Native code signing requires several network requests and is prone to many different types of errors from the Apple servers. To generate a production build that is code signed for the App Store, we recommend using [EAS Build](/build/introduction). 214 215When you compile your app onto a Simulator, the Simulator's native error logs will be piped to the Expo CLI process in the terminal. This is useful for quickly seeing bugs that may cause a fatal error. For example, missing permission messages. Error piping is not available for physical iOS devices. 216 217You can debug using `lldb` and all of the native Apple debugging tools by opening the project in Xcode and rebuilding from Xcode: 218 219<Terminal cmd={['$ xed ios']} /> 220 221Building from Xcode is useful because you can set native breakpoints and profile any part of the application. Be sure to track changes in source control (git) in case you need to regenerate the native app with `npx expo prebuild -p ios --clean`. 222 223**iOS development signing** 224 225If you want to see how your app will run on your device, all you have to do is connect it, run `npx expo run:ios —-device`, and select your connected device. 226 227Expo CLI will automatically sign the device for development, install the app, and launch it. 228 229If you don't have any developer profiles setup on your computer then you'll need to set them up manually outside of Expo CLI by following this guide: [Setup Xcode signing](https://expo.fyi/setup-xcode-signing). 230 231### Exporting 232 233You can export the JavaScript and assets for your app using Metro bundler by running: 234 235<Terminal cmd={['$ npx expo export']} /> 236 237This is done automatically when using `eas update` or when compiling the native runtime. The `export` command works similar to most web frameworks: 238 239- A bundler transpiles and bundles your application code for **production** environments, stripping all code guarded by the `__DEV__` boolean. 240- All static files are copied into a static `dist/` folder which can be served from a static host. 241- Contents of the `public/` folder are copied into the `dist/` folder as-is. 242 243The following options are provided: 244 245- `--platform <platform>`: Choose the platform to compile for: 'ios', 'android', 'all'. **Default: all**. 'web' is also available if configured in the app config. For more information, see [Customizing Metro](/guides/customizing-metro). 246- `--dev`: Bundle for **development** environments without minifying code or stripping the `__DEV__` boolean. 247- `--output-dir <dir>`: The directory to export the static files to. **Default: dist** 248- `--max-workers <number>`: Maximum number of tasks to allow the bundler to spawn. Setting this to `0` will run all transpilation on the same process, meaning you can easily debug Babel transpilation. 249- `-c, --clear`: Clear the bundler cache before exporting. 250- `--no-minify`: Skip minifying JavaScript and CSS assets (SDK 49 and above). 251 252### Exporting with webpack 253 254> webpack is only supported for the Web platform. 255 256You can export the JavaScript and assets for your web app using webpack by running the following: 257 258<Terminal cmd={['$ npx expo export:web']} /> 259 260- `--dev`: Bundle in 'development' mode without minifying code or stripping the `__DEV__` boolean. 261- `-c, --clear`: Clear the bundler cache before exporting. 262 263This command will be disabled if your project is configured to use `metro` for bundling web projects in the `app.json` via the `expo.web.bundler: 'metro'` field. 264 265## Prebuild 266 267<Terminal cmd={['$ npx expo prebuild']} /> 268 269Native source code must be generated before a native app can compile. Expo CLI provides a unique and powerful system called _prebuild_, that generates the native code for your project. To learn more, read the [Expo Prebuild docs](/workflow/prebuild.mdx). 270 271## Config 272 273Evaluate the app config (**app.json**, or **app.config.js**) by running: 274 275<Terminal cmd={['$ npx expo config']} /> 276 277- `--full`: Include all project config data. 278- `--json`: Output in JSON format, useful for converting an `app.config.js` to an `app.config.json`. 279- `-t, --type`: [Type of config](#config-type) to show. 280 281### Config Type 282 283There are three different config types that are generated from the app config: 284 285- `public`: The manifest file to use with OTA updates. Think of this like an `index.html` file's `<head />` element but for native apps. 286- `prebuild`: The config that is used for [Expo Prebuild](/workflow/prebuild) including async modifiers. This is the only time the config is not serializable. 287- `introspect`: A subset of the `prebuild` config that only shows in-memory modifications like `Info.plist` or `AndroidManifest.xml` changes. Learn more about [introspection](/config-plugins/development-and-debugging/#introspection). 288 289## Install 290 291Unlike the web, React Native is not backwards compatible. This means that npm packages often need to be the exact right version for the currently installed copy of `react-native` in your project. Expo CLI provides a best-effort tool for doing this using a list of popular packages and the known working version combinations. Simply use the `install` command as a drop-in replacement for `npm install`: 292 293<Terminal cmd={['$ npx expo install expo-camera']} /> 294 295Running a single instance of this command, you can also install multiple packages: 296 297<Terminal cmd={['$ npx expo install typescript expo-sms']} /> 298 299You can directly pass arguments to the underlying package manager by using the `--` operator: 300 301<Terminal 302 cmd={['$ yarn expo install typescript -- -D', '# yarn add typescript -D']} 303 cmdCopy="yarn expo install typescript -- -D" 304/> 305 306### Version validation 307 308You can perform validation and correction with the `--check` and `--fix` flags: 309 310- `--check`: Check which installed packages need to be updated. 311- `--fix`: Automatically update any invalid package versions. 312 313Example: 314 315<Terminal 316 cmd={[ 317 '# Check all packages for incorrect versions, prompt to fix locally', 318 '$ npx expo install --check', 319 ]} 320 cmdCopy="npx expo install --check" 321/> 322 323`npx expo install --check` prompts you about packages that are installed incorrectly. It also prompts about installing these packages to their compatible versions locally. It exits with non-zero in Continuous Integration (CI). This means you can use this to do continuous immutable validation. In contrast, `npx expo install --fix` will always fix packages if needed, regardless of the environment. 324 325You can validate specific packages by passing them: 326 327<Terminal 328 cmd={[ 329 '# Check only react-native and expo-sms', 330 '$ npx expo install react-native expo-sms --check', 331 ]} 332 cmdCopy="npx expo install react-native expo-sms --check" 333/> 334 335The command `npx expo install expo-camera` and `npx expo install expo-camera --fix` serve the same purpose, the `--fix` command is useful for upgrading all packages in your project like: 336 337<Terminal cmd={['$ npx expo install --fix']} /> 338 339### Configuring dependency validation 340 341> Available in SDK 49 and above. 342 343There may be circumstances where you want to use a version of a package is different from the version recommended by `npx expo install`. 344 345For example, you are testing a new version of `react-native-reanimated` to verify that it works well in your app and fixes a bug that you encountered. Now you want to 1) not be warned by `npx expo start` or `npx expo-doctor` and 2) not have that package version changed when you run `npx expo install --fix`. 346 347You can exclude specific packages from the version checks while still allowing the `install` command to install, check, and fix any other dependencies. This configuration extends to the checking done by `npx expo-doctor`. 348 349To exclude packages from version checking, set the `expo.install` config object in your project's **package.json**: 350 351```json package.json 352{ 353 "expo": { 354 "install": { 355 "exclude": ["expo-updates", "expo-splash-screen"] 356 } 357 } 358} 359``` 360 361### Install package managers 362 363`npx expo install` has support for `yarn`, `npm`, and `pnpm`. 364 365You can force the package manager using a named argument: 366 367- `--npm`: Use `npm` to install dependencies. Default when **package-lock.json** exists. 368- `--yarn`: Use `yarn` to install dependencies. Default when **yarn.lock** exists. 369- `--pnpm`: Use `pnpm` to install dependencies. Default when **pnpm-lock.yaml** exists. 370 371## Authentication 372 373Expo CLI provides authentication methods to use with the `npx expo start` command. Authentication is used to "code sign" manifests for secure OTA usage. Think of this like HTTPS on the web. 374 3751. Register an account with `npx expo register`. 3762. Login to your account with `npx expo login`. 3773. Check which account is currently authenticated with `npx expo whoami`. 3784. Logout with `npx expo logout`. 379 380These credentials are shared across Expo CLI and EAS CLI. 381 382## Customizing 383 384Sometimes you may want to customize a project file that would otherwise be generated in memory by Expo CLI. When utilizing tools other than Expo CLI, you'll need to have the default config files present, otherwise your app may not work as expected. You can generate files by running: 385 386<Terminal cmd={['$ npx expo customize']} /> 387 388From here, you can choose to generate basic project files like: 389 390- **babel.config.js** -- The Babel configuration. This is required to be present if you plan to use tooling other than Expo CLI to bundle your project. 391- **webpack.config.js** -- The default webpack config for web development. 392- **metro.config.js** -- The default Metro config for universal development. This is required for usage with `npx react-native`. 393 394## Environment Variables 395 396| Name | Type | Description | 397| ----------------------------------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | 398| `HTTP_PROXY` | **string** | HTTP/HTTPS proxy URL to connect for all network requests. Configures [https-proxy-agent](https://www.npmjs.com/package/https-proxy-agent). | 399| `EXPO_NO_WEB_SETUP` | **boolean** | Prevents the CLI from forcing web dependencies (`react-dom`, `react-native-web`, `@expo/webpack-config`) to be installed before using web functionality.<br/>This is useful for cases where you wish to perform non-standard web development. | 400| `EXPO_OFFLINE` | **boolean** | Skip all network requests when applicable. This leads to faster development in areas with poor network connection. | 401| `EXPO_NO_TYPESCRIPT_SETUP` | **boolean** | Prevents the CLI from forcing TypeScript to be configured on `npx expo start`.<br/>For more information, see [TypeScript guide](/guides/typescript/). | 402| `DEBUG=expo:*` | **string** | Enables debug logs for the CLI, you can configure this using the [`debug` convention](https://github.com/debug-js/debug#conventions). | 403| `EXPO_DEBUG` | **boolean** | An alias for `DEBUG=expo:*`. | 404| `EXPO_PROFILE` | **boolean** | Enable profiling stats for the CLI, this does not profile your application. | 405| `EXPO_NO_CACHE` | **boolean** | Disable all global caching. By default, app config JSON schemas, Expo Go binaries for simulators and emulators, and project templates are cached in the global **.expo** folder on your machine. | 406| `CI` | **boolean** | When enabled, the CLI will disable interactive functionality, skip optional prompts, and fail on non-optional prompts.<br/>Example: `CI=1 npx expo install --check` will fail if any installed packages are outdated. | 407| `EXPO_NO_TELEMETRY` | **boolean** | Disables anonymous usage collection. [Learn more about telemetry](#telemetry). | 408| `EXPO_NO_GIT_STATUS` | **boolean** | Skips warning about git status during potentially dangerous actions like `npx expo prebuild --clean`. | 409| `EXPO_NO_REDIRECT_PAGE` | **boolean** | Disables the redirect page for selecting an app, that shows when a user has `expo-dev-client` installed, and starts the project with `npx expo start` instead of `npx expo start --dev-client`. | 410| `EXPO_PUBLIC_FOLDER` | **string** | Public folder path to use with Metro for web. [Learn more about customizing Metro](/guides/customizing-metro/).<br/>Default: `public` | 411| `EDITOR` | **string** | Name of the editor to open when pressing <kbd>O</kbd> in the Terminal UI. This value is used across many command line tools. | 412| `EXPO_EDITOR` | **string** | An Expo-specific version of the `EDITOR` variable which takes higher priority when defined. | 413| `EXPO_IMAGE_UTILS_NO_SHARP` | **boolean** | Disable the usage of global Sharp CLI installation in favor of the slower Jimp package for image manipulation. This is used in places like `npx expo prebuild` for generating app icons. | 414| `EXPO_TUNNEL_SUBDOMAIN` | **boolean** | <StatusTag status="experimental" /><br/>Disable using `exp.direct` as the hostname for `--tunnel` connections. This enables **https://** forwarding which can be used to test universal links on iOS. This may cause unexpected issues with `expo-linking` and Expo Go. Select the exact subdomain to use by passing a `string` value that is not one of: `true`, `false`, `1`, `0`. | 415| `EXPO_METRO_NO_MAIN_FIELD_OVERRIDE` | **boolean** | Force Expo CLI to use the [`resolver.resolverMainFields`](https://facebook.github.io/metro/docs/configuration/#resolvermainfields) from the project's **metro.config.js** for all platforms. By default, Expo CLI will use `['browser', 'module', 'main']`, which is the default for webpack, for the web and the user-defined main fields for other platforms. | 416| `EXPO_NO_INSPECTOR_PROXY` | **boolean** | <StatusTag note="SDK 49+" /><br/>Disable the customized inspector proxy with improved support for the Chrome DevTools protocol.<br/>This includes support for the network inspector. | 417| `EXPO_NO_CLIENT_ENV_VARS` | **boolean** | <StatusTag note="SDK 49+" /><br/>Prevent inlining `EXPO_PUBLIC_` environment variables in client bundles. | 418| `EXPO_NO_DOTENV` | **boolean** | <StatusTag note="SDK 49+" /><br/>Prevent all `.env` file loading across Expo CLI. | 419| `EXPO_NO_METRO_LAZY` | **boolean** | Prevent adding the `lazy=true` query parameter to Metro URLs (`[email protected]` and greater). This disables `import()` support. | 420| `EXPO_USE_TYPED_ROUTES` | **boolean** | Use `expo.experiments.typedRoutes` to enable statically typed routes in Expo Router. | 421 422## Telemetry 423 424Expo dev tools collect anonymous data about general usage. This helps us know when a feature is not working as expected. Telemetry is completely optional, you can opt out by using the `EXPO_NO_TELEMETRY=1` environment variable. 425 426[ngrok]: https://ngrok.com 427