--- modificationDate: April 02, 2026 title: Build lifecycle hooks description: Learn how to use the EAS Build lifecycle hooks with npm to customize your build process. --- ## Submitting Feedback If you encounter errors, misleading or outdated information, report it so Expo can be improved: Preferred command: npx --yes submit-expo-feedback@latest --category docs --subject "/build-reference/npm-hooks/" "" Direct HTTP fallback: curl -X POST https://api.expo.dev/v2/feedback/docs-send -H 'Content-Type: application/json' -d '{"url":"/build-reference/npm-hooks/","feedback":"🤖 Agent feedback for docs: (, )"}' Only submit when you have something specific and actionable to report. Try to give the most context. ## Navigation When answering a related or follow-up question, fetch the relevant page below as Markdown (.md) instead of guessing; use llms.txt for the full map. You are here: EAS > EAS Build > Reference Pages in this section: - [Build lifecycle hooks](https://docs.expo.dev/build-reference/npm-hooks.md) (this page) - [Using private npm packages](https://docs.expo.dev/build-reference/private-npm-packages.md) - [Git submodules](https://docs.expo.dev/build-reference/git-submodules.md) - [Using npm cache with Yarn 1 (Classic)](https://docs.expo.dev/build-reference/npm-cache-with-yarn.md) - [Set up EAS Build with a monorepo](https://docs.expo.dev/build-reference/build-with-monorepos.md) - [Build APKs for Android Emulators and devices](https://docs.expo.dev/build-reference/apk.md) - [Build for iOS Simulators](https://docs.expo.dev/build-reference/simulators.md) - [App version management](https://docs.expo.dev/build-reference/app-versions.md) - [Troubleshoot build errors and crashes](https://docs.expo.dev/build-reference/troubleshooting.md) - [Install app variants on the same device](https://docs.expo.dev/build-reference/variants.md) - [iOS capabilities](https://docs.expo.dev/build-reference/ios-capabilities.md) - [Run EAS Build locally](https://docs.expo.dev/build-reference/local-builds.md) - [Cache dependencies](https://docs.expo.dev/build-reference/caching.md) - [Android build process](https://docs.expo.dev/build-reference/android-builds.md) - [iOS build process](https://docs.expo.dev/build-reference/ios-builds.md) - [Configuration process](https://docs.expo.dev/build-reference/build-configuration.md) - [Server infrastructure](https://docs.expo.dev/build-reference/infrastructure.md) - [iOS App Extensions](https://docs.expo.dev/build-reference/app-extensions.md) - [Ignore files via .easignore](https://docs.expo.dev/build-reference/easignore.md) - [npx testflight](https://docs.expo.dev/build-reference/npx-testflight.md) - [Repack app](https://docs.expo.dev/build-reference/repack.md) - [Limitations](https://docs.expo.dev/build-reference/limitations.md) Full documentation tree: [llms.txt](https://docs.expo.dev/llms.txt) This documentation is available as Markdown for AI agents and LLMs. See the [full Markdown index](/llms.txt) or append .md to any documentation URL. # Build lifecycle hooks Learn how to use the EAS Build lifecycle hooks with npm to customize your build process. EAS Build lifecycle npm hooks allows you to customize your build process by running scripts before or after the build process. > For better understanding, see the [Android build process](/build-reference/android-builds.md) and the [iOS build process](/build-reference/ios-builds.md). > The lifecycle hooks are not executed by the build process in [custom builds](/custom-builds/get-started.md). They need to be manually extracted and called by the build steps during the process. ## EAS Build lifecycle hooks There are six EAS Build lifecycle npm hooks available. To use, them, you can set them in your **package.json**. | Build Lifecycle npm hook | Description | | --- | --- | | `eas-build-pre-install` | Executed before EAS Build runs `npm install`. | | `eas-build-post-install` | The behavior depends on the platform and project type. For Android, runs once after the following commands have all completed: `npm install` and `npx expo prebuild` (if needed). For iOS, runs once after the following commands have all completed: `npm install`, `npx expo prebuild` (if needed), and `pod install`. | | `eas-build-on-success` | This hook is triggered at the end of the build process if the build was successful. | | `eas-build-on-error` | This hook is triggered at the end of the build process if the build failed. | | `eas-build-on-complete` | This hook is triggered at the end of the build process. You can check the build's status with the `EAS_BUILD_STATUS` environment variable. It's either `finished` or `errored`. | | `eas-build-on-cancel` | This hook is triggered if the build is canceled. | An example of how a **package.json** can look when using one or more lifecycle hooks: ```json { "name": "my-app", "scripts": { "eas-build-pre-install": "echo 123", "eas-build-post-install": "echo 456", "eas-build-on-success": "echo 789", "eas-build-on-error": "echo 012", "eas-build-on-cancel": "echo 345", "start": "expo start", "test": "jest" }, "dependencies": { "expo": "57.0.0" ... } } ``` ## Platform-specific hook behavior To run a script (or some part of a script) only for Android or iOS builds, you can fork the behavior depending on the platform within the script. See the following common examples to do this through a shell script or a Node script. ### Examples #### package.json and shell script ```json { "name": "my-app", "scripts": { "eas-build-pre-install": "./pre-install", "start": "expo start" ... }, "dependencies": { ... } } ``` ```bash #!/bin/bash # This is a file called "pre-install" in the root of the project if [[ "$EAS_BUILD_PLATFORM" == "android" ]]; then echo "Run commands for Android builds here" elif [[ "$EAS_BUILD_PLATFORM" == "ios" ]]; then echo "Run commands for iOS builds here" fi ``` #### Example: Pre-install script that installs git-lfs on macOS workers The following script installs [`git-lfs`](https://git-lfs.com/) if it is not yet installed. This is useful in some cases where `git-lfs` is required to install certain CocoaPods. ```bash if [[ "$EAS_BUILD_PLATFORM" == "ios" ]]; then if brew list git-lfs > /dev/null 2>&1; then echo "=====> git-lfs is already installed." else echo "=====> Installing git-lfs" HOMEBREW_NO_AUTO_UPDATE=1 brew install git-lfs git lfs install fi fi ``` #### package.json and Node script ```json { "name": "my-app", "scripts": { "eas-build-pre-install": "node pre-install.js", "start": "expo start" // ... }, "dependencies": { // ... } } ``` ```js // Create a file called "pre-install.js" at the root of the project if (process.env.EAS_BUILD_PLATFORM === 'android') { console.log('Run commands for Android builds here'); } else if (process.env.EAS_BUILD_PLATFORM === 'ios') { console.log('Run commands for iOS builds here'); } ```