API Solutions on Ruby On Rails

Rabl

"ruby templating system for generating JSON, XML, MessagePack, PList and BSON"

https://github.com/nesquena/rabl

ActiveModel::Serializers

Create serializer on ROR

https://github.com/rails-api/active_model_serializers

Rocket Pants

"API building tools on top of ActionController."

https://github.com/Sutto/rocket_pants

versionist

"A plugin for versioning Rails based RESTful APIs."

https://github.com/bploetz/versionist