The OS gem allows for some useful and easy functions, like OS.windows? (=> true or false) OS.bits ( => 32 or 64) etc"

Uglifier minifies JavaScript files by wrapping UglifyJS to be accessible in Ruby

Manipulate images with minimal use of memory via ImageMagick / GraphicsMagick

Hashdiff is a diff lib to compute the smallest difference between two hashes.

Daemons provides an easy way to wrap existing ruby scripts (for example a self-written server) to be run as a daemon and to be controlled by simple start/stop/restart commands. You can also call blocks as daemons and control them from the parent or just daemonize the current process. Besides this basic functionality, daemons offers many advanced features like exception backtracing and logging (in case your ruby script crashes) and monitoring and automatic restarting of your processes if they crash.

Simple, feature rich ascii table generation library

Retriable is a simple DSL to retry failed code blocks with randomized exponential backoff. This is especially useful when interacting external api/services or file system calls.

This gem aims at being a simple and reliable solution for controlling external programs running in the background on any Ruby / OS combination.

Convert directories, rpms, python eggs, rubygems, and more to rpms, debs, solaris packages and more. Win at package management without wasting pointless hours debugging bad rpm specs!

Easy upload management for ActiveRecord

Supervisors, Supervision Groups, and Supervision Trees for Celluloid.

Notifications, Internals, Logging, Probe, and essential Celluloid pieces demanding Supervision

Classes to support examples, benchmarks, or add special functionality.

Simple finite state machines with integrated Celluloid timeout support.

An implementation of an actor pool, based on the Celluloid concurrent object framework.

XPath is a Ruby DSL for generating XPath expressions

Parallel tests across CI server nodes based on each test file's time execution. It generates a test time execution report and uses it for future test runs.

Ruby integrations for Elasticsearch (client, API, etc.)

Record your test suite's HTTP interactions and replay them during future test runs for fast, deterministic, accurate tests.

Capybara is an integration testing tool for rack based web applications. It simulates how a user would interact with a website