Ruby on Rails
Jbuilder: generate JSON objects with a Builder-style DSL
A Relational Algebra
A virtual machine for Ruby on Rails core development
Rails Console on the Browser.
Rails application preloader
Ruby on Rails unobtrusive scripting adapter.
rubyonrails.org site anno 2015
Identify app models with a URI
Connects business objects and REST web services
Rack-based asset packaging system
Rails observer (removed from core in Rails 4.0)
Brings back `assigns` and `assert_template` to your Rails tests
Github hooks to provide an encouraging atmosphere for new contributors
Sprockets Rails integration
Action caching for Action Pack (removed from core in Rails 4.0)
Static page caching for Action Pack (removed from core in Rails 4.0)
XML parameters parser for Action Pack (removed from core in Rails 4.0)
Benchmark and profile your Rails apps
Ruby CoffeeScript Compiler
Ruby on Rails unobtrusive scripting adapter for jQuery
A gem to automate using jQuery with Rails
Extracting DomAssertions and SelectorAssertions from ActionView.
Active Record's Session Store extracted from Rails