# Licensee *A Ruby Gem to detect under what license a project is distributed.* [](https://travis-ci.org/benbalter/licensee) [](http://badge.fury.io/rb/licensee) [](https://coveralls.io/github/benbalter/licensee?branch=rspec) ## The problem * You've got an open source project. How do you know what you can and can't do with the software? * You've got a bunch of open source projects, how do you know what their licenses are? * You've got a project with a license file, but which license is it? Has it been modified? ## The solution Licensee automates the process of reading `LICENSE` files and compares their contents to known licenses using a several strategies (which we call "Matchers"). It attempts to determine a project's license in the following order: * If the license file has an explicit copyright notice, and nothing more (e.g., `Copyright (c) 2015 Ben Balter`), we'll assume the author intends to retain all rights, and thus the project isn't licensed. * If the license is an exact match to a known license. If we strip away whitespace and copyright notice, we might get lucky, and direct string comparison in Ruby is cheap. * If we still can't match the license, we use a fancy math thing called the [Sørensen–Dice coefficient](https://en.wikipedia.org/wiki/S%C3%B8rensen%E2%80%93Dice_coefficient), which is really good at calculating the similarity between two strings. By calculating the percent changed from the known license to the license file, you can tell, e.g., that a given license is 95% similar to the MIT license, that 5% likely representing legally insignificant changes to the license text. *Special thanks to [@vmg](https://github.com/vmg) for his Git and algorithmic prowess.* ## Installation `gem install licensee` or add `gem 'licensee'` to your project's `Gemfile`. ## Documentation See [the docs folder](/docs) for more information. You may be interested in: * [Instructions for using Licensee](docs/usage.md) * [Customizing Licensee's behavior](docs/customizing.md) * [Contributing to Licensee](CONTRIBUTING.md) (and development instructions) * More information about [what Licensee looks at](docs/what-we-look-at.md) (or doesn't, and why) ## Semantic Versioning This project conforms to [semver](http://semver.org/). As a result of this policy, you can (and should) specify a dependency on this gem using the [Pessimistic Version Constraint](http://guides.rubygems.org/patterns/) with two digits of precision. For example: spec.add_dependency 'licensee', '~> 1.0' This means your project is compatible with licensee 1.0 up until 2.0. You can also set a higher minimum version: spec.add_dependency 'licensee', '~> 1.1'