CSL-Ruby provides a Ruby parser and a comprehensive API for the Citation Style Language (CSL), an XML-based format to describe the formatting of citations, notes and bibliographies.

Styles and Locales

You can load CSL styles and locales by passing a respective XML string, file name, or URL. You can also load styles and locales by name if the corresponding files are installed in your local styles and locale directories. By default, CSL-Ruby looks for CSL styles and locale files in


You can change these locations by changing the value of CSL::Style.root and CSL::Locale.root respectively.

Alternatively, you can gem install csl-styles to install all official CSL styles and locales. To make the styles and locales available, simply require 'csl/styles.


CSL-Ruby is broadly aimed at two very different usage scenarios: on the one hand, you can use the parser to load existing styles and locales and manipulate, query or otherwise work with them using a dedicated API: that is to say, you do not have to resort to XML-related methods of access, but can make use of a large set of library methods which are specific to CSL. This is useful, primarily, for citation processors like CiteProc-Ruby.

On the other hand, CSL-Ruby makes it easy to create new styles and locales using Ruby; this is useful, for example, if you need to change or adapt styles on-the-fly or for writing an interactive style editor.

To get you started, here are a few usage examples; for the full set of available features, please consult the API documentation.

require 'csl'

# Load a style from the Zotero style repository
jps = CSL::Style.load 'http://zotero.org/styles/american-journal-of-political-science'

# Query style information
jps.title #-> "American Journal of Political Science"
jps.independent? #-> true
jps.citation_format #-> :"author-date"

# Validate style against the CSL schema
jps.valid? #-> true

# Load another style
amc = CSL::Style.load 'http://zotero.org/styles/applied-mathematics-and-computation'

amc.independent? #-> false

# Load the independent parent style
parent = amc.independent_parent
parent.title #-> "Elsevier (numeric, with titles)"

# Load standard CSL styles and locales from csl-styles gem
# Requires you to gem install csl-styles
require 'csl/styles'

# Load a locally installed style
apa = CSL::Style.load :apa

# Fetch the a macro
authors = apa.macros['authors'].children[0]
#-> #<CSL::Style::Names variable="author" children=[2]>

# Load a locally installed locale
fr = CSL::Locale.load :fr

# Translate a term
fr.translate 'editor' #-> "éditeur"
fr.translate 'editor', plural: true #-> "éditeurs"
fr.translate 'editor', form: 'short' #-> "éd."

# Ordinalize a number
fr.ordinalize 42 #=> "42ᵉ"
fr.ordinalize 3, form: 'long' => "troisième"

# Create a new style
style = CSL::Style.new

style.id = 'http://www.zotero.org/styles/my-style'
style.title = 'My Style'

# Add the default license for CSL styles

# Access the style as XML

# Access the style as XML (pretty printed)


CSL-Ruby was written with portability in mind. For performance reasons it will use Nokogiri for XML parsing and validation if available; however, CSL-Ruby will fallback to REXML from the Ruby standard library. In order to use Nokogiri, simply gem install nokogiri or add it to your Gemfile.


The CSL-Ruby source code is hosted on GitHub. You can check out a copy of the latest code using Git:

$ git clone https://github.com/inukshuk/csl-ruby.git

To get started, install the development dependencies and run all tests:

$ cd csl-ruby
$ bundle install
$ rake

If you've found a bug or have a question, please open an issue on the issue tracker. Or, for extra credit, clone the CSL-Ruby repository, write a failing example, fix the bug and submit a pull request.


Thanks to Rintze M. Zelle, Sebastian Karcher, Frank G. Bennett, Jr., and Bruce D'Arcus of CSL and citeproc-js fame for their support!

Thanks to Google and the Berkman Center at Harvard University for supporting this project as part of Google Summer of Code.

Copyright 2009-2020 Sylvester Keil. All rights reserved.

Copyright 2012 President and Fellows of Harvard College.


CSL-Ruby is dual licensed under the AGPL and the FreeBSD license.