Capistrano is a utility and framework for executing commands in parallel on multiple remote machines, via SSH.

Signet is an OAuth 1.0 / OAuth 2.0 implementation.

Easy upload management for ActiveRecord

Net::SSH: a pure-Ruby implementation of the SSH2 client protocol. It allows you to write programs that invoke and interact with processes on remote servers, via SSH2.

kaminari-core includes pagination logic independent from ORMs and view libraries

kaminari-actionview provides pagination helpers for your Action View templates

kaminari-activerecord lets your Active Record models be paginatable

This gem is used by GitHub to render any fancy markup such as Markdown, Textile, Org-Mode, etc. Fork it and add your own!

A generalized Rack framework for multiple-provider authentication.

A secure, non-evaling end user template engine with aesthetic markup.

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

A modern, highly customizable, and responsive Jekyll theme for documentation with built-in search.

memoize methods invocation

Fluentd is an open source data collector designed to scale and simplify log management. It can collect, process and ship many kinds of data in near real-time.

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

Simple mime type detection using magic numbers, filenames, and extensions

Manipulate images with minimal use of memory via ImageMagick / GraphicsMagick

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...

Simple, feature rich ascii table generation library

A high-level IO library that provides validation, type conversion, and more for command-line interfaces. HighLine also includes a complete menu system that can crank out anything from simple list selection to complete shells with just minutes of work.