Bower Build Status

A package manager for the web

It offers a generic, unopinionated solution to the problem of front-end package management, while exposing the package dependency model via an API that can be consumed by a more opinionated build stack. There are no system wide dependencies, no dependencies are shared between different apps, and the dependency tree is flat.

Bower runs over Git, and is package-agnostic. A packaged component can be made up of any type of asset, and use any type of transport (e.g., AMD, CommonJS, etc.).

View all packages available through Bower's registry.


$ npm install -g bower

Bower depends on Node.js and npm. Also make sure that git is installed as some bower packages require it to be fetched and installed.


Much more information is available via bower help once it's installed. This is just enough to get you started.

Installing packages and dependencies

Bower offers several ways to install packages:

Using the dependencies listed in the current directory's bower.json
$ bower install
Using a local or remote package
$ bower install <package>
Using a specific version of a package
$ bower install <package>#<version>
Using a different name and a specific version of a package
$ bower install <name>=<package>#<version>

Where <package> can be any one of the following:

  • A name that maps to a package registered with Bower, e.g, jquery. ‡
  • A public remote Git endpoint, e.g., git:// ‡
  • A private Git repository, e.g., If the protocol is https, a prompt will ask for the credentials. ssh can also be used, e.g., and can authenticate with the user's ssh public/private keys. ‡
  • A local endpoint, i.e., a folder that's a Git repository. ‡
  • A public remote Subversion endpoint, e.g., svn+ ‡
  • A private Subversion repository, e.g., svn+ssh:// or svn+ ‡
  • A local endpoint, i.e., a folder that's an Subversion repository, e.g., svn+file:///path/to/svn/. ‡
  • A shorthand endpoint, e.g., someone/some-package (defaults to GitHub). ‡
  • A URL to a file, including zip and tar files. Its contents will be extracted.

‡ These types of <package> might have versions available. You can specify a semver compatible version to fetch a specific release, and lock the package to that version. You can also specify a range of versions.

If you are using a package that is a git endpoint, you may use any tag, commit SHA, or branch name as a version. For example: <package>#<sha>. Using branches is not recommended because the HEAD does not reference a fixed commit SHA.

If you are using a package that is a subversion endpoint, you may use any tag, revision number, or branch name as a version. For example: <package>#<revision>.

All package contents are installed in the bower_components directory by default. You should never directly modify the contents of this directory.

Using bower list will show all the packages that are installed locally.

N.B. If you aren't authoring a package that is intended to be consumed by others (e.g., you're building a web app), you should always check installed packages into source control.

Custom install directory

A custom install location can be set in a .bowerrc file using the directory property. The .bowerrc file should be a sibling of your project's bower.json.

  "directory": "app/components"

Finding packages

To search for packages registered with Bower:

$ bower search [<name>]

Using just bower search will list all packages in the registry.

Using packages

We discourage using bower components statically for performance and security reasons (if component has an upload.php file that is not ignored, that can be easily exploited to do malicious stuff).

The best approach is to process components installed by bower with build tool (like Grunt or gulp), and serve them concatenated or using module loader (like RequireJS).

Uninstalling packages

To uninstall a locally installed package:

$ bower uninstall <package-name>


On prezto or oh-my-zsh, do not forget to alias bower='noglob bower' or bower install jquery\#1.9.1

Running commands with sudo

Bower is a user command, there is no need to execute it with superuser permissions. However, if you still want to run commands with sudo, use --allow-root option.

A note for Windows users

To use Bower on Windows, you must install msysgit correctly. Be sure to check the option shown below:


Note that if you use TortoiseGit and if Bower keeps asking for your SSH password, you should add the following environment variable: GIT_SSH - C:\Program Files\TortoiseGit\bin\TortoisePlink.exe. Adjust the TortoisePlink path if needed.

Using bower's cache

Bower supports installing packages from its local cache (without internet connection), if the packages were installed before.

$ bower install <package-name> --offline

The content of the cache can be listed with:

$ bower cache list

The cache can be cleaned with:

$ bower cache clean


Bower can be configured using JSON in a .bowerrc file.

The current spec can be read here in the Configuration section.

Running on a continuous integration server

Bower will skip some interactive and analytics operations if it finds a CI environmental variable set to true. You will find that the CI variable is already set for you on many continuous integration servers, e.g., CircleCI and Travis-CI.

You may try to set manually set CI variable manually before running your Bower commands. On Mac or Linux, export CI=true and on Windows set CI=true

Interactive configuration

If for some reason you are unable to set the CI environment variable, you can alternately use the --config.interactive=false flag. (bower install --config.interactive=false)

Defining a package

You must create a bower.json in your project's root, and specify all of its dependencies. This is similar to Node's package.json, or Ruby's Gemfile, and is useful for locking down a project's dependencies.

NOTE: In versions of Bower before 0.9.0 the package metadata file was called component.json rather than bower.json. This has changed to avoid a name clash with another tool. You can still use component.json for now but it is deprecated and the automatic fallback is likely to be removed in an upcoming release.

You can interactively create a bower.json with the following command:

$ bower init

The bower.json (spec) defines several options, including:

  • name (required): The name of your package.
  • version: A semantic version number (see semver).
  • main [string|array]: The primary endpoints of your package.
  • ignore [array]: An array of paths not needed in production that you want Bower to ignore when installing your package.
  • dependencies [hash]: Packages your package depends upon in production. Note that you can specify ranges of versions for your dependencies.
  • devDependencies [hash]: Development dependencies.
  • private [boolean]: Set to true if you want to keep the package private and do not want to register the package in future.
  "name": "my-project",
  "description": "My project does XYZ...",
  "version": "1.0.0",
  "main": "path/to/main.css",
  "ignore": [
  "dependencies": {
    "<name>": "<version>",
    "<name>": "<folder>",
    "<name>": "<package>"
  "devDependencies": {
    "<test-framework-name>": "<version>"

Registering packages

To register a new package:

  • There must be a valid manifest JSON in the current working directory.
  • Your package should use semver Git tags.
  • Your package must be available at a Git endpoint (e.g., GitHub); remember to push your Git tags!

Then use the following command:

$ bower register <my-package-name> <git-endpoint>

The Bower registry does not have authentication or user management at this point in time. It's on a first come, first served basis. Think of it like a URL shortener. Now anyone can run bower install <my-package-name>, and get your library installed.

There is no direct way to unregister a package yet. For now, you can request a package be unregistered.

Consuming a package

Bower also makes available a source mapping. This can be used by build tools to easily consume Bower packages.

If you pass the --paths option to Bower's list command, you will get a simple name-to-path mapping:

  "backbone": "bower_components/backbone/index.js",
  "jquery": "bower_components/jquery/index.js",
  "underscore": "bower_components/underscore/index.js"

Alternatively, every command supports the --json option that makes bower output JSON. Command result is outputted to stdout and error/logs to stderr.

Programmatic API

Bower provides a powerful, programmatic API. All commands can be accessed through the bower.commands object.

var bower = require('bower');

.install(['jquery'], { save: true }, { / custom config / })
.on('end', function (installed) {

.search('jquery', {})
.on('end', function (results) {

Commands emit four types of events: log, prompt, end, error.

  • log is emitted to report the state/progress of the command.
  • prompt is emitted whenever the user needs to be prompted.
  • error will only be emitted if something goes wrong.
  • end is emitted when the command successfully ends.

For a better of idea how this works, you may want to check out our bin file.

When using bower programmatically, prompting is disabled by default. Though you can enable it when calling commands with interactive: true in the config. This requires you to listen for the prompt event and handle the prompting yourself. The easiest way is to use the inquirer npm module like so:

var inquirer =  require('inquirer');

.install(['jquery'], { save: true }, { interactive: true })
// ..
.on('prompt', function (prompts, callback) {
    inquirer.prompt(prompts, callback);

Completion (experimental)

NOTE: Completion is still not implemented for the 1.0.0 release

Bower now has an experimental completion command that is based on, and works similarly to the npm completion. It is not available for Windows users.

This command will output a Bash / ZSH script to put into your ~/.bashrc, ~/.bash_profile, or ~/.zshrc file.

$ bower completion >> ~/.bash_profile



We welcome contributions of all kinds from anyone. Please take a moment to review the guidelines for contributing.

Bower Team

Core team

Thanks for assistance and contributions:

@addyosmani, @ahmadnassri, @angus-c, @borismus, @carsonmcdonald, @chriseppstein, @danwrong, @davidmaxwaterman, @desandro, @hemanth, @isaacs, @josh, @jrburke, @kennethklee, @marcelombc, @marcooliveira, @mklabs, @MrDHat, @necolas, @richo, @rvagg, @ryanflorence, @SlexAxton, @sstephenson, @tomdale, @uzquiano, @visionmedia, @wagenet, @wycats

Bower Alumni


Copyright (c) 2014 Twitter and other contributors

Licensed under the MIT License