Awesome Ruby

A collection of awesome Ruby libraries, tools, frameworks and software.

Inspired by awesome-php, awesome-python, frontend-dev-bookmarks and ruby-bookmarks.

Contributions are always welcome! Please take a look at the contribution guidelines and quality standard first.

Thanks to all contributors, you're awesome and wouldn't be possible without you! The goal is to build a categorized community-driven collection of very well-known resources.

• Awesome Ruby
  • Coding Style Guides
  • Package Management
  • Environment Management
  • Documentation
  • Testing
  • Web Frameworks
  • Web Servers
  • Database Drivers
  • Database Tools
  • ORM/ODM
  • ORM/ODM Extensions
  • Decorators
  • HTTP
  • API Builder
  • CLI Builder
  • Authentication
  • OAuth
  • Authorization
  • Logging
  • Queue
  • Scheduling
  • Data Visualization
  • Template Engine
  • Assets
  • Markdown Processors
  • Search
  • Internationalization
  • Country Data
  • Geolocation
  • Money
  • Caching
  • File Upload
  • Email
  • Form Builder
  • Pagination
  • Imagery
  • Video
  • WebSocket
  • HTML/XML Parsing
  • Ebook
  • PDF
  • Web Crawling
  • Processes and Threads
  • Process Monitoring
  • Concurrency
  • Configuration
  • Core Extensions
  • Error Handling
  • Code Analysis and Metrics
  • Dashboards
  • Debugging Tools
  • Date and Time Processing
  • Profiler
  • Third-party APIs
  • CMS
  • Admin Interface
  • Static Site Generation
  • SEO
  • Social Networking
  • E-Commerce and Payments
  • Analytics
  • RSS
  • DevOps Tools
  • Git Tools
  • GUI
  • Game Development
  • Mobile Development
  • Robotics
  • Natural Language Processing
  • Machine Learning
  • Abstraction
  • Misc
• Services and Apps
• Resources
• Other Awesome Lists

Coding Style Guides

• Ruby style guide - Community-driven Ruby coding style
• Rails style guide - Community-driven Rails best practices and style for Rails 3 and 4
• RSpec style guide - Better Specs { rspec guidelines with ruby }

Package Management

• Gems
  • RubyGems - Community's gem hosting service
  • Bundler - Manage your application's gem dependencies with less pain
• Packages and Applications
  • Homebrew - The missing package manager for OS X
  • Homebrew-cask - a CLI workflow for the administration of Mac applications distributed as binaries
  • CocoaPods - The Objective-C dependency manager
  • Berkshelf - A Chef Cookbook manager

Environment Management

• rbenv — Use rbenv to pick a Ruby version for your application and guarantee that your development environment matches production
• RVM — RVM is a command-line tool which allows you to easily install, manage, and work with multiple ruby environments from interpreters to sets of gems
• ruby-build - Compile and install Ruby
• chruby - Change your current Ruby. No shims, no crazy options or features, ~90 LOC
• chgems - Chroot for RubyGems
• ruby-install - Installs Ruby, JRuby, Rubinius, MagLev or MRuby
• fry - Simple ruby version manager for fish

Documentation

• RDoc - RDoc produces HTML and command-line documentation for Ruby projects
• YARD - YARD enables the user to generate consistent, usable documentation that can be exported to a number of formats very easily
• grape-swagger - Add swagger compliant documentation to your Grape API
• Inch - Inch is a documentation measurement and evalutation tool for Ruby code, based on YARD

Testing

• Frameworks
  • RSpec - Behaviour Driven Development for Ruby
  • minitest - minitest provides a complete suite of testing facilities supporting TDD, BDD, mocking, and benchmarking
  • Test::Unit - Test::Unit is a xUnit family unit testing framework for Ruby
  • Cucumber - BDD that talks to domain experts first and code second
  • Capybara - Acceptance test framework for web applications
  • RR - A test double framework that features a rich selection of double techniques and a terse syntax
  • Spinach - Spinach is a high-level BDD framework that leverages the expressive Gherkin language (used by Cucumber) to help you define executable specifications of your application or library's acceptance criteria.
  • Bacon - A small RSpec clone
  • Konacha - Test your Rails application's JavaScript with the mocha test framework and chai assertion library
  • shoulda-matchers - Provides Test::Unit- and RSpec-compatible one-liners that test common Rails functionality. These tests would otherwise be much longer, more complex, and error-prone.
  • Spork - A DRb server for testing frameworks (RSpec / Cucumber currently)
  • Cutest - Isolated tests in Ruby
• Fake Data
  • factory_girl - A library for setting up Ruby objects as test data
  • faker - A library for generating fake data such as names, addresses, and phone numbers.
  • Fabrication - A simple and powerful object generation library
  • Machinist - Fixtures aren't fun. Machinist is
  • Forgery - Easy and customizable generation of forged data.
• Mock
  • WebMock - Library for stubbing and setting expectations on HTTP requests
  • ActiveMocker - Generate mocks from ActiveRecord models for unit tests that run fast because they don’t need to load Rails or a database.
• WebDrivers
  • Watir - Web application testing in Ruby
  • Selenium WebDriver - This gem provides Ruby bindings for WebDriver.
• Extra
  • Appraisal - Appraisal integrates with bundler and rake to test your library against different versions of dependencies
  • timecop - Provides "time travel" and "time freezing" capabilities, making it dead simple to test time-dependent code
  • Ruby-JMeter - A Ruby based DSL for building JMeter test plans
  • Spring - Preloads your rails environment in the background for faster testing and Rake tasks
  • vcr - Record your test suite's HTTP interactions and replay them during future test runs for fast, deterministic, accurate tests

Web Frameworks

• Ruby on Rails - A web-application framework that includes everything needed to create database-backed web applications according to the Model-View-Controller (MVC) pattern
• Sinatra - Classy web-development dressed in a DSL
• Padrino - A full-stack ruby framework built upon Sinatra
• Lotus - It aims to bring back Object Oriented Programming to web development, leveraging on a stable API, a minimal DSL, and plain objects.
• Camping - A web microframework which consistently stays at less than 4kB of code
• Cuba - A microframework for web development
• Pakyow - A framework for building modern web-apps in Ruby. It helps you build working software faster with a development process that remains friendly to both designers and developers
• Ramaze - A simple, light and modular open-source web application framework written in Ruby
• Roda - A routing tree web framework

Web Servers

• Rack - A common Ruby web server interface. By itself, it's just a specification and utility library, but all Ruby web servers implement this interface
• Phusion Passenger - Fast and robust web server and application server
• Unicorn - Rack HTTP server for fast clients and Unix
• Thin - Tiny, fast & funny HTTP server
• Puma - A modern, concurrent web server for Ruby
• Goliath - A non-blocking Ruby web server framework

Database Drivers

• ruby-pg - Ruby interface to PostgreSQL 8.3 and later
• mysql2 - A modern, simple and very fast Mysql library for Ruby (binding to libmysql)
• SQLite3
• redis-rb - A Ruby client that tries to match Redis' API one-to-one, while still providing an idiomatic interface
• Redic - Lightweight Redis Client
• DataObjects - An attempt to rewrite existing Ruby database drivers to conform to one, standard interface.
• mongo-ruby-driver - MongoDB Ruby driver
• moped - A MongoDB driver for Ruby

Database Tools

• Seed dump - Rails 4 task to dump (parts) of your database to db/seeds.rb.
• Seed Fu - Advanced seed data handling for Rails.

ORM/ODM

• ActiveRecord
• Sequel - Sequel is a simple, flexible, and powerful SQL database access toolkit for Ruby
• Mongoid - An ODM (Object-Document-Mapper) framework for MongoDB in Ruby
• DataMapper - ORM which works well with legacy databases. Last release (1.2.0) was on 13 October 2011.
• MongoMapper
• MongoModel - Ruby ODM for interfacing with MongoDB databases
• ohm - Object-hash mapping library for Redis
• Guacamole - An ODM for ArangoDB

ORM/ODM Extensions

• Mongoid Tree - A tree structure for Mongoid documents using the materialized path pattern

Decorators

• Draper - Draper adds an object-oriented layer of presentation logic to your Rails application

HTTP

• RESTClient - Simple HTTP and REST client for Ruby, inspired by microframework syntax for specifying actions
• httparty
• Faraday
• Sawyer - Secret user agent of HTTP, built on top of Faraday
• excon - Usable, fast, simple Ruby HTTP 1.1. It works great as a general HTTP(s) client and is particularly well suited to usage in API clients.
• Patron - Patron is a Ruby HTTP client library based on libcurl.
• Typhoeus - Typhoeus wraps libcurl in order to make fast and reliable requests
• Http Client - Gives something like the functionality of libwww-perl (LWP) in Ruby
• http - The HTTP Gem: a simple Ruby DSL for making HTTP requests.
• Savon - Savon is a SOAP client for the Ruby programming language.

API Builder

• Grape - An opinionated micro-framework for creating REST-like APIs in Ruby
• Rails::API - Rails for API only applications
• ActiveModel::Serializers - JSON serialization of objects
• Crêpe - The thin API stack
• jbuilder - Create JSON structures via a Builder-style DSL
• Jsonite - A tiny, HAL-compliant JSON presenter for your APIs
• rabl - General ruby templating with json, bson, xml, plist and msgpack support
• Pliny - Opinionated template Sinatra app for writing excellent APIs in Ruby
• Roar - Resource-Oriented Architectures in Ruby

CLI Builder

• Rake - A make-like build utility for Ruby
• Thor - A toolkit for building powerful command-line interfaces
• Commander - The complete solution for Ruby command-line executables
• Slop - Simple Lightweight Option Parsing
• Main - A class factory and DSL for generating command line programs real quick
• GLI - Git-Like Interface Command Line Parser

Authentication

• Devise - A flexible authentication solution for Rails based on Warden
• Authlogic
• OmniAuth - A library that standardizes multi-provider authentication utilizing Rack middleware
• Sorcery - Magical Authentication for Rails 3 and 4
• Clearance - Small and simple email & password based authenticaton for Rails

OAuth

• OAuth2 - A Ruby wrapper for the OAuth 2.0 protocol
• Doorkeeper - An OAuth2 provider for Rails

Authorization

• CanCanCan
• Pundit - Minimal authorization through OO design and pure Ruby classes
• Authority ORM-neutral way to authorize actions in your Rails app.

Logging

• Log4r - Log4r is a comprehensive and flexible logging library for use in Ruby programs
• Logging - A flexible logging library for use in Ruby programs based on the design of Java's log4j library.
• Lograge - An attempt to tame Rails' default policy to log everything.
• Cabin - Structured+contextual logging experiments in Ruby.
• Yell - Your Extensible Logging Library
• MongoDB Logger - MongoDB logger for Rails
• Fluentd - Fluentd collects events from various data sources and writes them to files, database or other types of storages
• HttpLog - Log outgoing HTTP requests.
• Scrolls - Simple logging

Queue

• Resque — A Redis-backed Ruby library for creating background jobs
• Sidekiq — A full-featured background processing framework for Ruby. It aims to be simple to integrate with any modern Rails application and much higher performance than other existing solutions.
• Sucker Punch — A single process background processing library using Celluloid. Aimed to be Sidekiq's little brother.
• Delayed::Job — Database backed asynchronous priority queue
• active_job - Declare job classes that can be run by a variety of queueing backends

Scheduling

• Whenever - A Ruby gem that provides a clear syntax for writing and deploying cron jobs
• Clockwork - Clockwork is a cron replacement. It runs as a lightweight, long-running Ruby process which sits alongside your web processes (Mongrel/Thin) and your worker processes (DJ/Resque/Minion/Stalker) to schedule recurring work at particular times or dates.
• rufus-scheduler - Job scheduler for Ruby (at, cron, in and every jobs)
• resque-scheduler - A light-weight job scheduling system built on top of Resque

Data Visualization

• Ruby/GraphViz - Ruby interface to the GraphViz graphing tool
• RailRoady - Ruby on Rails 3/4 model and controller UML class diagram generator.
• Rails Erd - Generate Entity-Relationship Diagrams for Rails applications.

Template Engine

• Tilt - Generic interface to multiple Ruby template engines
• Haml - HTML Abstraction Markup Language
• Slim - A template language whose goal is reduce the syntax to the essential parts without becoming cryptic
• Liquid - Safe, customer facing template language for flexible web apps
• Mustache - Logic-less Ruby templates
• Curly - A template language that completely separates structure and logic

Assets

• Sass - Sass makes CSS fun again
• Less - Leaner CSS, in your browser or Ruby.
• Less Rails - The dynamic stylesheet language for the Rails asset pipeline.
• Management:
  • Sprockets - Rack-based asset packaging system
  • Rails Assets - Bundler to Bower proxy

Markdown Processors

• kramdown — Kramdown is yet-another-markdown-parser but fast, pure Ruby, using a strict syntax definition and supporting several common extensions
• Redcarpet — A fast, safe and extensible Markdown to (X)HTML parser
• Maruku — A pure-Ruby Markdown-superset interpreter

Search

• Thinking Sphinx - A library for connecting ActiveRecord to the Sphinx full-text search tool
• elasticsearch-ruby
• Sunspot - A Ruby library for expressive, powerful interaction with the Solr search engine
• Searchkick - Searchkick learns what your users are looking for. As more people search, it gets smarter and the results get better. It’s friendly for developers - and magical for your users.
• pg_search - Builds ActiveRecord named scopes that take advantage of PostgreSQL's full text search
• has_scope - Has scope allows you to easily create controller filters based on your resources named scopes.
• Searchlogic - Object based searching, common named scopes, and other useful named scope tools for ActiveRecord
• attr_searchable - Search engine like fulltext query support for ActiveRecord
• ransack - Object-based searching.
• Rroonga - The Ruby bindings of Groonga

Internationalization

• i18n - Ruby Internationalization and localization solution
• i18n-tasks - Manage missing and unused translations with the awesome power of static analysis
• twitter-cldr-rb - Ruby implementation of the ICU (International Components for Unicode) that uses the Common Locale Data Repository to format dates, plurals, and more
• r18n - Advanced i18n library for Rails, Sinatra, desktop apps, models, works well with complex languages like Russian.

Country Data

• Carmen - A repository of geographic regions
• Countries - All sorts of useful information about every country packaged as pretty little country objects
• i18n_data - country/language names and 2-letter-code pairs, in 85 languages, for country/language i18n
• normalize_country - Convert country names and codes to a standard, includes a conversion program for XMLs, CSVs and DBs

Geolocation

• Geocoder - A complete geocoding solution for Ruby. With Rails it adds geocoding (by street or IP address), reverse geocoding (find street address based on given coordinates), and distance queries
• Geokit - Geokit gem provides geocoding and distance/heading calculations

Money

• Money - A Ruby Library for dealing with money and currency conversion
• eu_central_bank - A gem that calculates the exchange rate using published rates from European Central Bank

Caching

• Action caching for Action Pack - Action caching for Action Pack
• Dalli - A high performance pure Ruby client for accessing memcached servers
• Record Cache - Cache Active Model Records in Rails 3

File Upload

• CarrierWave - Classier solution for file uploads for Rails, Sinatra and other Ruby web frameworks
• PaperClip - Easy file attachment management for ActiveRecord
• DragonFly - A Ruby gem for on-the-fly processing - suitable for image uploading in Rails, Sinatra and much more!
• rack-secure-upload - Upload files securely

Email

• Mail - A Really Ruby Mail Library
• Pony- The express way to send mail from Ruby
• Mailman - An incoming mail processing microframework in Ruby
• Incoming - Incoming! helps you receive email in your Rack apps
• MailCatcher - Catches mail and serves it through a dream
• LetterOpener - Preview mail in the browser instead of sending.

Form Builder

• Simple Form - Rails forms made easy
• Formtastic - A Rails form builder plugin with semantically rich and accessible markup
• Rails Bootstrap Forms - Rails form builder that makes it super easy to create beautiful-looking forms with Twitter Bootstrap 3+
• Abracadabra - The gem that swaps out text with a fully-compliant Rails form in one click

Pagination

• Kaminari - A Scope & Engine based, clean, powerful, customizable and sophisticated paginator for modern web app frameworks and ORMs
• will_paginate - A pagination library that integrates with Ruby on Rails, Sinatra, Merb, DataMapper and Sequel

Imagery

• MiniMagick - A ruby wrapper for ImageMagick or GraphicsMagick command line
• RMagick - RMagick is an interface between Ruby and ImageMagick
• PSD.rb - Parse Photoshop files in Ruby with ease

Video

• Streamio FFMPEG - Simple yet powerful wrapper around the ffmpeg command for reading metadata and transcoding movies

WebSocket

• Faye - A set of tools for simple publish-subscribe messaging between web clients. It ships with easy-to-use message routing servers for Node.js and Rack applications, and clients that can be used on the server and in the browser.
• Websocket-Rails - Creates a built in WebSocket server inside a Rails application with ease. Also support streaming HTTP
• Sync - Real-time Rails Partials
• Firehose - Build realtime Ruby web applications
• Rails Realtime - Adding Real-Time To Your RESTful Rails App.

HTML/XML Parsing

• Nokogiri - An HTML, XML, SAX, and Reader parser with XPath and CSS selector support
• HappyMapper - Object to XML mapping library, using Nokogiri
• ROXML - Custom mapping and bidirectional marshalling between Ruby and XML using annotation-style class methods, via Nokogiri or LibXML.

Ebook

• Bookshop - Bookshop is a an open-source agile book development and publishing framework for authors, editors.
• Git Scribe - Basically the best way to write an ebook.
• Review - Re:VIEW is flexible document format/conversion system
• Gepub - A generic EPUB library for Ruby : supports EPUB 3
• Eeepub - EeePub is a Ruby ePub generator.
• Mobi - A Ruby way to read MOBI format metadata

PDF

• Prawn - Fast, Nimble PDF Writer for Ruby
• Pdfkit - HTML+CSS to PDF using wkhtmltopdf
• Wicked Pdf - PDF generator (from HTML) plugin for Ruby on Rails
• Kitabu - A framework for creating e-books from Markdown/Textile text markup using Ruby.
• Gimli - Utility for converting markup files to pdf files.
• Shrimp - A phantomjs based pdf renderer
• RGhost - RGhost is a document creation and conversion API.
• Wisepdf - Wkhtmltopdf wrapper done right

Web Crawling

• MetaInspector - Ruby gem for web scraping purposes. It scrapes a given URL, and returns you its title, meta description, meta keywords, an array with all the links, all the images in it, etc.
• LinkThumbnailer - Ruby gem that generates thumbnail images and videos from a given URL. Much like popular social website with link preview.
• anemone - Ruby library and CLI for crawling websites.
• Wombat - Web scraper with an elegant DSL that parses structured data from web pages
• Mechanize - Mechanize is a ruby library that makes automated web interaction easy.

Processes and Threads

• Parallel - Run any code in parallel Processes (> use all CPUs) or Threads (> speedup blocking operations). Best suited for map-reduce or e.g. parallel downloads/uploads
• posix-spawn - Fast Process::spawn for Rubys >= 1.8.7 based on the posix_spawn() system interfaces
• childprocess - Cross-platform ruby library for managing child processes.
• forkoff - brain-dead simple parallel processing for ruby

Process Monitoring

• Bluepill - Simple process monitoring tool
• God - An easy to configure, easy to extend monitoring framework written in Ruby

Concurrency

• EventMachine - An event-driven I/O and lightweight concurrency library for Ruby
• Celluloid - Actor-based concurrent object framework for Ruby
• Concurrent Ruby - Modern concurrency tools including agents, futures, promises, thread pools, supervisors, and more. Inspired by Erlang, Clojure, Scala, Go, Java, JavaScript, and classic concurrency patterns.

Configuration

• Configatron - Simple and feature rich configuration system for Ruby apps
• Configus - Helps you easily manage environment specific settings
• dotenv - Loads environment variables from .env
• Econfig - Flexible configuration for Rails applications
• Figaro - Simple, Heroku-friendly Rails app configuration using ENV and a single YAML file
• Global - Provides accessor methods for your configuration data
• RailsConfig - Multi-environment yaml settings for Rails3

Core Extensions

• ActiveSupport - A collection of utility classes and standard library extensions.
• Ruby Facets - The premiere collection of general purpose method extensions and standard additions for Ruby.
• Attributes
  • ActiveAttr - What ActiveModel left out
  • Virtus - Attributes on Steroids for Plain Old Ruby Objects
  • FastAttributes - FastAttributes adds attributes with their types to the class
• Hash
  • Hashie - A collection of tools that extend Hashes and make them more useful

Error Handling

• Exception Notification - A set of notifiers for sending notifications when errors occur in a Rack/Rails application
• Errbit - The open source, self-hosted error catcher
• Airbrake - The official Airbrake library for Ruby on Rails (and other Rack based frameworks)
• Better Errors - Better error page for Rack apps
• Raven Ruby - Raven is a Ruby client for Sentry.
• Nesty - Nested exceptions for Ruby

Code Analysis and Metrics

• SimpleCov - Code coverage for Ruby 1.9+ with a powerful configuration library and automatic merging of coverage across test suites.
• Rubocop - A static code analyzer, based on the community Ruby style guide.
• rails_best_practices - A code metric tool for rails projects
• Flay - Flay analyzes code for structural similarities. Differences in literal values, variable, class, method names, whitespace, programming style, braces vs do/end, etc are all ignored. Making this totally rad.
• Flog - Flog reports the most tortured code in an easy to read pain report. The higher the score, the more pain the code is in.
• Rubycritic - A Ruby code quality reporter.
• Brakeman - A static analysis security vulnerability scanner for Ruby on Rails applications.
• fukuzatsu - Complexity analysis tool with a rich web front-end.
• Reek - Code smell detector for Ruby

Dashboards

• Dashing-Rails - The exceptionally handsome dashboard framework for Rails.

Date and Time Processing

• business_time - Support for doing time math in business hours and days
• Chronic - A natural language date/time parser written in pure Ruby
• time-lord - Adds extra functionality to the time class
• time_diff - Calculates the difference between two time
• validates_timeliness - Date and time validation plugin for ActiveModel and Rails
• groupdate - The simplest way to group temporal data in ActiveRecord, arrays and hashes

Debugging Tools

• debugger - A port of ruby-debug that works on 1.9.2 and 1.9.3.
• Byebug - A simple to use, feature rich debugger for Ruby 2.

Profiler

• ruby-prof - A code profiler for MRI rubies
• rack-mini-profiler - Profiler for your development and production Ruby rack apps
• perftools.rb - gperftools (formerly known as google-perftools) for Ruby code
• Peek - Visual status bar showing Rails performance
• bullet - Help to kill N+1 queries and unused eager loading

Third-party APIs

• Octokit - Ruby toolkit for the GitHub API
• gitlab - Ruby wrapper and CLI for the GitLab API
• fb_graph - A full-stack Facebook Graph API wrapper
• twitter - A Ruby interface to the Twitter API
• t - A command-line power tool for Twitter
• tweetstream - A simple library for consuming Twitter's Streaming API
• ruby-gmail - A Rubyesque interface to Gmail
• gmail - A Rubyesque interface to Gmail, with all the tools you'll need.
• instagram-ruby-gem - The official gem for the Instagram REST and Search APIs
• soundcloud-ruby - Official SoundCloud API Wrapper for Ruby
• linkedin - Provides an easy-to-use wrapper for LinkedIn's REST APIs
• Yt - An object-oriented Ruby client for YouTube API V3
• youtube_it - An object-oriented Ruby wrapper for the YouTube GData API
• ruby-trello - Implementation of the Trello API for Ruby
• hipchat-rb - HipChat HTTP API Wrapper in Ruby with Capistrano hooks
• flickr - A Ruby interface to the Flickr API
• wikipedia - Ruby client for the Wikipedia API.
• Dropbox - Dropbox API Ruby Client.
• itunes_store_transporter - Ruby wrapper around Apple's iTMSTransporter program
• Pusher - Ruby server library for the Pusher API.

CMS

• Alchemy CMS - A powerful, userfriendly and flexible Open Source Rails CMS
• Refinery CMS - An open source Ruby on Rails content management system for Rails 3 and 4
• Radiant - A no-fluff, open source content management system designed for small teams
• LocomotiveCMS - A simple but powerful CMS based on Liquid templates and Mongodb database
• Publify - A self hosted Web publishing platform on Rails

Admin Interface

• ActiveAdmin - a Ruby on Rails framework for creating elegant backends for website administration
• RailsAdmin - A Rails engine that provides an easy-to-use interface for managing your data
• bhf - A simple to use Rails-Engine-Gem that offers an admin interface for trusted user

Static Site Generation

• Jekyll - Transform your plain text into static websites and blogs
• Middleman - A static site generator using all the shortcuts and tools in modern web development
• Nanoc - A static site generator, fit for building anything from a small personal blog to a large corporate web site
• High Voltage - Easily include static pages in your Rails app

SEO

• FriendlyId - The "Swiss Army bulldozer" of slugging and permalink plugins for Active Record
• MetaTags - A gem to make your Rails application SEO-friendly
• SitemapGenerator - A framework-agnostic XML Sitemap generator written in Ruby

Social Networking

• diaspora* - A privacy aware, distributed, open source social network
• Discourse - A platform for community discussion. Free, open, simple
• Forem - Rails 3 and Rails 4 forum engine
• Campo - Campo is a lightweight forum application, base on Ruby on Rails.

E-Commerce and Payments

• Active Merchant - A simple payment abstraction library extracted from Shopify
• Spree
• ROR Ecommerce
• stripe-ruby - Stripe Ruby bindings
• Paypal Merchant SDK - Official Paypal Merchant SDK for Ruby
• Shoppe - A Rails-based e-commerce platform which allows you to easily introduce a catalogue-based store into your Rails 4 applications

Analytics

• Gabba - Simple way to send server-side notifications to Google Analytics
• Ahoy - A solid foundation to track visits and events in Ruby, JavaScript, and native apps
• Staccato - Track analytics into the official Google Analytics Collection API
• Legato - Model analytics reports and queries against the official Google Analytics Reporting API

RSS

• Feedjira - A feed fetching and parsing library.
• Simple rss - A simple, flexible, extensible, and liberal RSS and Atom reader.
• Feed normalizer - Extensible Ruby wrapper for Atom and RSS parsers.
• Ratom - A fast, libxml based, Ruby Atom library.

DevOps Tools

• Capistrano - A remote server automation and deployment tool written in Ruby
• Backup - Provides an elegant DSL in Ruby for performing backups on UNIX-like systems
• Puppet - An automated administrative engine for your Linux, Unix, and Windows systems, performs administrative tasks (such as adding users, installing packages, and updating server configurations) based on a centralized specification
• Vagrant - Create and configure lightweight, reproducible, and portable development environments
• Chef - A systems integration framework, built to bring the benefits of configuration management to your entire infrastructure
• Mina - Really fast deployer and server automation tool.
• Lita - ChatOps for Ruby: A pluggable chat bot framework usable with any chat service.
• Logstash - Logs/event transport, processing, management, search
• Rubber - The rubber plugin enables relatively complex multi-instance deployments of RubyOnRails applications to Amazon's Elastic Compute Cloud (EC2).

Git Tools

• hub - a command line tool that wraps Git in order to extend it with extra features and commands that make working with GitHub easier
• Rugged - Ruby bindings to libgit2
• git-auto-bisect - Find the commit that broke master
• git-whence - Find which merge a commit came from
• git-spelunk - Dig through git blame history
• git-up - Fetch and rebase all locally-tracked remote branches

GUI

• Shoes
• QtRuby - Qt4 binding for ruby
• RubyGnome2

Game Development

• Gosu - A 2D game development library for the Ruby and C++ programming languages

Mobile Development

• RubyMotion - A revolutionary toolchain that lets you quickly develop and test native iOS and OS X applications for iPhone, iPad and Mac
• Ruboto - A platform for developing full stand-alone apps for Android using the Ruby language and libraries

Robotics

• Artoo - Next generation robotics framework with support for different platforms: Arduino, Leap Motion, Pebble, Raspberry Pi, etc.

Natural Language Processing

• Treat - Treat is a toolkit for natural language processing and computational linguistics in Ruby

Machine Learning

• PredictionIO Ruby SDK - The PredictionIO Ruby SDK provides a convenient API to quickly record your users' behavior and retrieve personalized predictions for them
• Ruby Datumbox Wrapper - It's a simple Ruby Datumbox Wrapper. At the moment the API currently allows you to build applications that make use of machine learning algorithms.

Abstraction

• Interactor - Interactor provides a common interface for performing complex interactions in a single request
• Light Service - Series of Actions with an emphasis on simplicity.
• Mutations - Compose your business logic into commands that sanitize and validate input
• Cells - View Components for Rails
• Reform - Form objects decoupled from models.

Misc

• Betty - Friendly English-like interface for your command line. Don't remember a command? Ask Betty
• Termit - Google Translate with speech synthesis in your terminal
• Foreman - Manage Procfile-based applications
• Pry - A powerful alternative to the standard IRB shell for Ruby
• Pry Debugger - Pry navigation commands via debugger (formerly ruby-debug)
• Guard - A command line tool to easily handle events on file system modifications
• play ► - Your company's dj
• Treetop - PEG (Parsing Expression Grammar) parser
• Yomu - Read text and metadata from files and documents (.doc, .docx, .pages, .odt, .rtf, .pdf)
• AASM - A library for adding finite state machines to Ruby classes
• Gollum - A simple, Git-powered wiki with a sweet API and local frontend.
• JsonCompare - Returns the difference between two JSON files
• pygments.rb - A Ruby wrapper for the Python pygments syntax highlighter
• Ruby Operators - A webpage showing awesome names for different Ruby operators.

Services and Apps

• GitHub - Powerful collaboration, code review, and code management for open source and private projects.
• GitLab - Open source software to collaborate on code.
• Gitlab CI - Integrate with your GitLab to run tests for your projects.
• Travis CI.org - A distributed build system for the open source community.
• Travis CI.com - Take care of running your tests and deploying your private apps.
• PullReview - Automated code review for Ruby and Rails - from style to security.
• HoundCI - Review your Ruby code for style guide violations.
• Hakiri - Ship Secure Ruby Apps.
• CodeClimate - Quality & security analysis for Ruby on Rails and Javascript.
• Gemnasium - Monitor your project dependencies and alert you about updates and security vulnerabilities.
• AppSignal - Better monitoring for your Rails applications.
• Honeybadger - Exception, uptime, and performance monitoring for Ruby.
• Inch CI - Documentation badges for Ruby projects.

Resources

• GitHub Explore
• Ruby5 - The latest news in the Ruby and Rails community
• The Ruby Toolbox - A comprehensive catalog of Ruby and Rails plug-ins, gems, tools and resources for Ruby developers with popularity ratings based on GitHub watchers and Gem downloads
• RubyFlow - Ruby Programming Community Link Blog
• RubyDaily - Community driven news
• Ruby Weekly - A free, once–weekly e-mail round-up of Ruby news and articles
• GemBundle - A place to discover new Ruby Gems

Other Awesome Lists

Other amazingly awesome lists can be found in the awesome-awesomeness list.