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Build Features for Customizing Deployments

Learn how to customize your deployments using Vercel's build features.
Table of Contents

Vercel provides the following features to customize your deployments:

When your project's code is using private npm modules that require authentication, you need to perform an additional step to install private modules.

To install private npm modules, define NPM_TOKEN as an Environment Variable in your project. Alternatively, define NPM_RC as an Environment Variable in the contents of the project's npmrc config file that resides at the root of the project folder and is named ~/.npmrc. This file defines the config settings of npm at the level of the project.

To learn more, check out the guide here if you need help configuring private dependencies.

Vercel ignores certain files and folders by default and prevents them from being uploaded during the deployment process for security and performance reasons. Please note that these ignored files are only relevant when using Vercel CLI.


A complete list of files and folders ignored by Vercel during the Deployment process.

The .vercel/output directory is not ignored when vercel deploy --prebuilt is used to deploy a prebuilt Vercel Project, according to the Build Output API specification.

You do not need to add any of the above files and folders to your .vercelignore file because it is done automatically by Vercel.

Vercel allows you to access the source code and build logs for your deployment using special pathnames for Logs and Source Protection. You can access this option from your project's Security settings.

All deployment URLs have two special pathnames to access the source code and the build logs:

  • /_src
  • /_logs

By default, these routes are protected so that they can only be accessed by you and the members of your Vercel Team.

Logs and Source Protection is enabled by default.

By appending /_src to a Deployment URL or Custom Domain in your web browser, you will be redirected to the Deployment inspector and be able to browse the sources and build outputs.

By appending /_logs to a Deployment URL or Custom Domain in your web browser, you will be able to see a real-time stream of logs from your deployment build processes by clicking on the Building accordion and Serverless Function invocations by clicking on the Functions tab.

The pathnames /_src and /_logs redirect to and require logging into your Vercel account to access any sensitive information. By default, a third-party can never access your source or logs by crafting a deployment URL with one of these paths.

You can configure these paths to make them publicly accessible under the Security tab on the Project Settings page. You can learn more about making paths publicly accessible in the Logs and Source Protection section.

On Vercel, you can deploy Git submodules with a Git provider as long as the submodule is publicly accessible through the HTTP protocol. Git submodules that are private or requested over SSH will fail during the Build step. However, you can reference private repositories formatted as npm packages in your package.json file dependencies. Private repository modules require a special link syntax that varies according to the Git provider. For more information on this syntax, see "How do I use private dependencies with Vercel?".

Last updated on June 22, 2024