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License Finder

Build Status Code Climate

With bundler it's easy for your project to depend on many gems. This decomposition is nice, but managing licenses becomes difficult. This tool gathers info about the licenses of the gems in your project.


Add license_finder to your Rails project's Gemfile and bundle:

gem 'license_finder', git: ""


License finder will generate reports of action items - i.e., dependencies that do not fall within your license "whitelist".

$ bundle exec license_finder

The first time you run this, license_finder will create a default configuration file ./config/license_finder.yml:

#- MIT
#- Apache 2.0
#- test
#- development

This allows you to configure bundler groups and add licenses to the whitelist.

On a brand new Rails project, you could expect license_finder to output something like the following (assuming you whitelisted the MIT license in your config/license_finder.yml):

Dependencies that need approval:

highline, 1.6.14, ruby
json, 1.7.5, ruby
mime-types, 1.19, ruby
rails, 3.2.8, other
rdoc, 3.12, other
rubyzip, 0.9.9, ruby
xml-simple, 1.1.1, other

The executable task will also write out a dependencies.yml, dependencies.txt, and dependencies.html file in the root of your project.

The latter two files are human readable reports that you could send to your non-technical business partners, lawyers, etc.

license_finder will also return a non-zero exit status if there are unapproved dependencies. You could use this in a CI build, for example, to alert you whenever someone adds an unapproved dependency to the project.

It will also merge in an existing dependencies.yml file, if one exists (i.e., you've previously run this command and then edited the resulting file).

Manually recording licenses

When you have dependencies marked as having an 'other' license, license_finder will output the license and readme file locations for the dependency, allowing you to manually research what the actual license is. Once this has been established, you can record this information with the -l option as such:

$ license_finder -l MIT my_unknown_dependency

This command would assign the MIT license to the dependency my_unknown_dependency.

Manually approving dependencies

Whenever you have a dependency that falls outside of your whitelist, license_finder will tell you. If your business decides that this is an acceptable risk, you can manually approve the dependency by using the -a or --approve option of the license_finder command.

For example, lets assume you've only whitelisted the "MIT" license in your config/license_finder.yml. You then add the 'awesome_gpl_gem' to your Gemfile, which we'll assume is licensed with the GPL license. You then run license_finder and see the gem listed in the output:

awesome_gpl_gem, 1.0.0, GPL

Your business tells you that in this case, it's acceptable to use this gem. You now run:

$ bundle exec license_finder -a awesome_gpl_gem

If you rerun license_finder, you should no longer see awesome_gpl_gem in the output.

Manually managing Javascript Dependencies

License Finder currently has no method for automatically detecting third-party javascript libraries in your application and alerting you to license violations. However, you can manually add javascript dependencies to your dependencies.yml file:

- name: "my_javascript_library"
  version: "0.0.0"
  license: "GPL"
  approved: false

You could then update the "approved" attribute to true once you have signoff from your business. License Finder will remember any manually added licenses between successive runs.

Usage with Rake

First, add license finder to your project's Gemfile:

gem "license_finder"

Next, update your project's Rakefile with the license finder rake task:

require 'bundler/setup'
require 'license_finder'

You can now run bundle exec rake license_finder. This is the equivalent of running bundle exec license_finder.

This could be handy if you have a build for CI that you want to break when you have unapproved dependencies. The rake task will exit 1 immediately if there are unapproved dependencies, stopping your build dead in its tracks!

A note to gem authors / maintainers

For the good of humanity, please add a license to your gemspec! do |s| = "my_great_gem"
  s.license = "MIT"

And add a LICENSE file to your gem that contains your license text.


LicenseFinder is released under the MIT License.

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