String#camelize Ruby Extension

Build Status Gem Version

fast_camelize is a C extension that provides a fast implementation of ActiveSupport's String#camelize method.

Is it fast?

At last check, these were the benchmarks (obtained by running bin/bench with ActiveSupport 6.1.3):

Warming up --------------------------------------
       ActiveSupport    20.000  i/100ms
        FastCamelize    74.000  i/100ms
Calculating -------------------------------------
       ActiveSupport    202.091  (± 7.4%) i/s -      1.020k in   5.081583s
        FastCamelize    974.025  (± 2.3%) i/s -      4.884k in   5.016944s

        FastCamelize:      974.0 i/s
       ActiveSupport:      202.1 i/s - 4.82x  (± 0.00) slower


Add this line to your application's Gemfile:

gem 'fast_camelize'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fast_camelize


After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at


The gem is available as open source under the terms of the MIT License.