Oj is compatible with Ruby 2.0.0, 2.1, 2.2, 2.3, 2.4 and RBX. Support for JRuby has been removed as JRuby no longer supports C extensions and there are bugs in the older versions that are not being fixed.


Although up until 4.1 Rails uses multi_json, an issue in Rails causes ActiveSupport to fail to make use Oj for JSON handling. There is a gem to patch this for Rails 3.2 and 4.0. As of the Oj 2.6.0 release the default behavior is to not use the to_json() method unless the :use_to_json option is set. This provides another work around to the rails older and newer behavior.

The latest ActiveRecord is able to work with Oj by simply using the line:

serialize :metadata, Oj

In version Rails 4.1, multi_json has been removed, and this patch is unnecessary and will no longer work. See Rails.