Byebug is a Ruby debugger. It's implemented using the TracePoint C API for execution control and the Debug Inspector C API for call stack navigation. The core component provides support that front-ends can build on. It provides breakpoint handling and bindings for stack frames among other things and it comes with an easy to use command line interface.
Pry is a runtime developer console and IRB alternative with powerful introspection capabilities. Pry aims to be more than an IRB replacement. It is an attempt to bring REPL driven programming to the Ruby language.
Bridge from Ruby to AppleScript to control Web Console