--- title: System environment variables product: vercel url: /docs/environment-variables/system-environment-variables type: reference prerequisites: - /docs/environment-variables related: - /docs/skew-protection summary: System environment variables are automatically populated by Vercel, such as the URL of the deployment or the name of the Git branch deployed. install_vercel_plugin: npx plugins add vercel/vercel-plugin --- # System environment variables Vercel provides a set of environment variables that are automatically populated by the system, such as the URL of the deployment or the name of the Git branch deployed. ## Automatically expose system environment variables To expose these environment variables to your deployments: 1. Navigate to your project on your [dashboard](/dashboard). 2. Open **Settings** in the sidebar and click on [**Environment Variables**](https://vercel.com/d?to=%2F%5Bteam%5D%2F%5Bproject%5D%2Fsettings%2Fenvironment-variables\&title=Go+to+Environment+Variables). 3. Select the **Automatically expose System Environment Variables** checkbox. > **⚠️ Warning:** If you disable this setting, no deployment ID will be made available for supported frameworks (like Next.js) to use, which means [Skew Protection](/docs/skew-protection) will also be disabled. ## System environment variables If you are using a framework for your project, Vercel provides the following prefixed environment variables: > **💡 Note:** When you choose to automatically expose system environment variables, some > React warnings, such as those in a `create-react-app` will display as build > errors. For more information on this error, see [How do I resolve a > `process.env.CI = true` > error?](/kb/guide/how-do-i-resolve-a-process-env-ci-true-error) ### `VERCEL` **Available at: **Both build and runtime An indicator to show that system environment variables have been exposed to your project's Deployments. ```bash VERCEL=1 ``` ### `CI` **Available at: **Build time An indicator that the code is running in a Continuous Integration environment. ```bash CI=1 ``` ### `VERCEL_ENV` **Available at: **Both build and runtime The environment that the app is deployed and running on. The value can be either production, preview, or development. ```bash VERCEL_ENV=production ``` ### `VERCEL_TARGET_ENV` **Available at: **Both build and runtime The system or custom environment that the app is deployed and running on. The value can be either production, preview, development, or the name of a custom environment. ```bash VERCEL_TARGET_ENV=production ``` ### `VERCEL_URL` **Available at: **Both build and runtime The domain name of the generated deployment URL. Example: \*.vercel.app. The value does not include the protocol scheme https://. ```bash VERCEL_URL=my-site.vercel.app ``` ### `VERCEL_BRANCH_URL` **Available at: **Both build and runtime The domain name of the generated Git branch URL. Example: \*-git-\*.vercel.app. The value does not include the protocol scheme https://. ```bash VERCEL_BRANCH_URL=my-site-git-improve-about-page.vercel.app ``` ### `VERCEL_PROJECT_PRODUCTION_URL` **Available at: **Both build and runtime A production domain name of the project. We select the shortest production custom domain, or vercel.app domain if no custom domain is available. Note, that this is always set, even in preview deployments. This is useful to reliably generate links that point to production such as OG-image URLs. The value does not include the protocol scheme https://. ```bash VERCEL_PROJECT_PRODUCTION_URL=my-site.com ``` ### `VERCEL_REGION` **Available at: **Runtime The ID of the Region where the app is running. ```bash VERCEL_REGION=cdg1 ``` ### `VERCEL_DEPLOYMENT_ID` **Available at: **Both build and runtime The unique identifier for the deployment, which can be used to implement Skew Protection. ```bash VERCEL_DEPLOYMENT_ID=dpl_7Gw5ZMBpQA8h9GF832KGp7nwbuh3 ``` ### `VERCEL_PROJECT_ID` **Available at: **Both build and runtime The unique identifier for the project. ```bash VERCEL_PROJECT_ID=prj_Rej9WaMNRbffVm34MfDqa4daCEvZzzE ``` ### `VERCEL_SKEW_PROTECTION_ENABLED` **Available at: **Both build and runtime When Skew Protection is enabled in Project Settings, this value is set to 1. ```bash VERCEL_SKEW_PROTECTION_ENABLED=1 ``` ### `VERCEL_AUTOMATION_BYPASS_SECRET` **Available at: **Both build and runtime The Protection Bypass for Automation value, if the secret has been generated in the project's Deployment Protection settings. ```bash VERCEL_AUTOMATION_BYPASS_SECRET=secret ``` ### `VERCEL_OIDC_TOKEN` **Available at: **Build time When Secure Backend Access with OpenID Connect (OIDC) Federation is enabled in Project Settings, this value is set to a Vercel-issued OIDC token. At runtime, the token is set to thex-vercel-oidc-tokenheader on your functions' Request object. In local development, you can download the token using the CLI commandvercel env pull. ```bash VERCEL_OIDC_TOKEN=secret ``` ### `VERCEL_GIT_PROVIDER` **Available at: **Both build and runtime The Git Provider the deployment is triggered from. ```bash VERCEL_GIT_PROVIDER=github ``` ### `VERCEL_GIT_REPO_SLUG` **Available at: **Both build and runtime The origin repository the deployment is triggered from. ```bash VERCEL_GIT_REPO_SLUG=my-site ``` ### `VERCEL_GIT_REPO_OWNER` **Available at: **Both build and runtime The account that owns the repository the deployment is triggered from. ```bash VERCEL_GIT_REPO_OWNER=acme ``` ### `VERCEL_GIT_REPO_ID` **Available at: **Both build and runtime The ID of the repository the deployment is triggered from. ```bash VERCEL_GIT_REPO_ID=117716146 ``` ### `VERCEL_GIT_COMMIT_REF` **Available at: **Both build and runtime The git branch of the commit the deployment was triggered by. ```bash VERCEL_GIT_COMMIT_REF=improve-about-page ``` ### `VERCEL_GIT_COMMIT_SHA` **Available at: **Both build and runtime The git SHA of the commit the deployment was triggered by. ```bash VERCEL_GIT_COMMIT_SHA=fa1eade47b73733d6312d5abfad33ce9e4068081 ``` ### `VERCEL_GIT_COMMIT_MESSAGE` **Available at: **Both build and runtime The message attached to the commit the deployment was triggered by. The message is truncated if it exceeds 2048 bytes. ```bash VERCEL_GIT_COMMIT_MESSAGE=Update about page ``` ### `VERCEL_GIT_COMMIT_AUTHOR_LOGIN` **Available at: **Both build and runtime The username attached to the author of the commit that the project was deployed by. ```bash VERCEL_GIT_COMMIT_AUTHOR_LOGIN=timmytriangle ``` ### `VERCEL_GIT_COMMIT_AUTHOR_NAME` **Available at: **Both build and runtime The name attached to the author of the commit that the project was deployed by. ```bash VERCEL_GIT_COMMIT_AUTHOR_NAME=Timmy Triangle ``` ### `VERCEL_GIT_PREVIOUS_SHA` **Available at: **Build time The git SHA of the last successful deployment for the project and branch. ```bash VERCEL_GIT_PREVIOUS_SHA=fa1eade47b73733d6312d5abfad33ce9e4068080 ``` ### `VERCEL_GIT_PULL_REQUEST_ID` **Available at: **Both build and runtime The pull request id the deployment was triggered by. If a deployment is created on a branch before a pull request is made, this value will be an empty string. ```bash VERCEL_GIT_PULL_REQUEST_ID=23 ``` --- [View full sitemap](/docs/sitemap)