To program Ruby, you will need a Ruby interpreter and an editor or IDE. This appendix lists the primary sources of Ruby and Rails development tools.
Some Ruby programmers like to use simple text editors and run programs from the command line; others like a fully integrated IDE with built-in debugging. Here are some possibilities.
3rdRail
http://www.embarcadero.com/products/3rdrail/
This is a commercial Rails-centric IDE for Eclipse. It currently supports Rails 1.x and 2.x only.
http://www.aptana.com/products/radrails/
This is a free Rails-centric IDE for Eclipse.
This is a free Ruby IDE for NetBeans. The future development of Ruby support in NetBeans has now been discontinued.
This is a commercial Ruby and Rails IDE for Visual Studio.
http://www.jetbrains.com/ruby/
This is a commercial Ruby IDE with emphasis on Rails.
This is a Ruby editor for Mac OS X.