SassC::Rails Build Status Gem Version

We all love working with Sass, but compilation can take quite a long time for larger codebases. This gem integrates the C implementation of Sass, LibSass, into the asset pipeline.

In one larger project, this made compilation 4x faster:

# Using sassc-rails

[1] pry(main)> { |bm| { Rails.application.assets["application.css"] } }
       user     system      total        real
   1.720000   0.170000   1.890000 (  1.936867)

# Using sass-rails

 [1] pry(main)> { |bm| { Rails.application.assets["application.css"] } }
       user     system      total        real
  7.820000   0.250000   8.070000 (  8.106347)

This should essentially be a drop in alternative to sass-rails.

Inline Source Maps

With SassC-Rails, it's also extremely easy to turn on inline source maps. Simply add the following configuration to your development.rb file:

# config/environments/development.rb
config.sass.inline_source_maps = true

After adding this config line, you may need to clear your assets cache (rm -r tmp/cache/assets), stop spring, and restart your rails server. You may also wish to disable line comments (config.sass.line_comments = false).

Note, as indicated, these source maps are inline. They will not generate additional files or anything like that. Instead, they will be appended to the compiled application.css file.

LibSass Compatibility With Ruby Sass

For a look at the compatibility between Ruby Sass and LibSass, check this compatibility chart out.


Add this line to your application's Gemfile:

gem 'sassc-rails'

And then execute:

$ bundle

Common Issues

Deployment to Heroku

Due to LibSass compilation requirements, you must upgrade to the Heroku Cedar-14 Stack in order to successfully install this gem.

Upgrading to Cedar-14 is usually a painless process.

Installing alongside a gem that depends on Sass-Rails

Libraries explicitly depending on Sass-Rails, such as ActiveAdmin, can cause conflicts with installation of SassC-Rails. While we have no built-in solution for this, please check out this issue for a workaround.


This gem is based on sass-rails, and is maintained by Ryan Boland and awesome contributors.



  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Add Tests
  5. Push to the branch (git push origin my-new-feature)
  6. Create a new Pull Request