pry

Pry is a runtime developer console and IRB alternative with powerful introspection capabilities. Pry aims to be more than an IRB replacement

$gem install pry

Official docs outline

Extra Credit builds an outline of pry's docs the first time your work uses it. Until then, start at the official documentation.

regexp_parser A library for tokenizing, lexing, and parsing Ruby regular expressions.
domain_name This is a Domain Name manipulation library for Ruby. It can also be used for cookie domain validation based on the Public Suffix List.
globalid URIs for your models makes it easy to pass references around.
websocket-driver WebSocket protocol handler with pluggable I/O
coderay Fast and easy syntax highlighting for selected languages, written in Ruby. Comes with RedCloth integration and LOC counter.
erubi Erubi is a ERB template engine for ruby. It is a simplified fork of Erubis
crass Crass is a pure Ruby CSS parser based on the CSS Syntax Level 3 spec.
sprockets Sprockets is a Rack-based asset packaging system that concatenates and serves JavaScript, CoffeeScript, CSS, Sass, and SCSS.
rubygems-update A package (also known as a library) contains a set of functionality that can be invoked by a Ruby program, such as reading and parsing an
actioncable Structure many real-time application concerns into channels over a single WebSocket connection.
puma Puma is a simple, fast, multi-threaded, and highly parallel HTTP 1.1 server for Ruby/Rack applications. Puma is intended for use in both dev
mini_portile2 Simple autoconf and cmake builder for developers. It provides a standard way to compile against dependency libraries without requiring syste