Pry
A runtime developer console and IRB alternative
...Dropping binding.pry into application code creates interactive breakpoints, making it easy to poke at variables, step through logic (with plugins like pry-byebug), and test hypotheses. An extensible command system and a rich plugin ecosystem add profiling, colorized output, paging, and Git integration. In day-to-day development, Pry shortens the feedback loop and turns debugging into an exploratory, conversational workflow.