* Active Record DB Adapters activerecord-jdbc-adapter, activerecord-sqlserver-adapter, activerecord-jdbcmysql-adapter, activerecord-jdbcpostgresql-adapter, activerecord-jdbcderby-adapter, and 3 more
* Active Record Default Values Default value for and Active record defaults
* Active Record Enumerations enumerize, Enumerated attribute, Simple enum, Active Enum, Classy Enum, and 8 more
* Active Record Index Assistants foreigner, Rails indexes, schema_plus, lol_dba, immigrant, and 3 more
* Active Record Named Scopes ransack, Searchlogic, Pacecar, randumb, Can search, and 7 more
* Active Record Nesting Awesome nested set, Ancestry, Acts as tree, Closure Tree, Better nested set, and 2 more
* Active Record Sharding Octopus, Db-charmer, masochism, multi_db, Data fabric, and 2 more
* Active Record Soft Delete rails3_acts_as_paranoid, paranoia, Acts as paranoid, Acts as archive, Permanent records, and 7 more
* Active Record Sortables Acts as list, ranked-model, Sortable, Resort, and acts_as_restful_list
* Active Record User Stamping Userstamp, User stamp, Acts as audited, Record activities, Acts as loggable, and 2 more
* Active Record Value Cleanup Attribute normalizer, Strip attributes, Nilify blanks, auto_strip_attributes, Scrubby, and 2 more
* Active Record Versioning PaperTrail, audited, Vestal Versions, Acts as versioned, Acts as revisable, and 11 more
* Pagination will_paginate, Kaminari, sorted, ajax_pagination, Paged scopes, and 3 more
* Rails Comments juvia, Acts as commentable with threading, Acts as commentable, Disqus, opinio, and 3 more
* Rails DB Bootstrapping Seed-fu, Populator, seedbank, Bootstrapper, Db-populate, and 3 more
* Rails Ratings Ajaxful-rating, ajaxful_rating, letsrate, Acts as rateable, mongoid_rateable, and 4 more
* Rails Search Sunspot, sunspot_rails, Tire, Thinking-sphinx, Rsolr, and 18 more
* Rails Tagging Acts-as-taggable-on, Is taggable, rocket_tag, Acts as taggable redux, Acts as taggable on steroids, and 3 more
* Background Processing
* Background Jobs Resque, Delayed job, sidekiq, Bunny, Beanstalkd, and 29 more
* Daemonizing Daemons, Daemon-kit, Daemon generator, dante, Robustthread, and 8 more
* Daemon Management foreman, Daemon controller, lunchy, and Daemon-spawn
* Scheduling Whenever, resque-scheduler, Rufus-scheduler, Clockwork, Craken, and 2 more
* Code Quality
* Code Metrics SimpleCov, Rails best practices, Rcov, rubocop, Cane, and 21 more
* Communication
* Asynchronous E-Mail Resque Mailer, Mail queue, Mailhopper, Resque Mail Queue, and Popthis
* CRM Apps Fat free crm, Mongo crm, railscrm, myitcrm2, Cohort, and 3 more
* E-Mail Preview Letter Opener, MailCatcher, mail_view, Rails Email Preview, sanitize_email, and 1 more
* E-Mail Processing Mailman, Fetcher, griddler, newman, Mail fetcher, and 3 more
* E-Mail Sending Action Mailer, Mail, Pony, Tmail, capistrano_mailer, and 2 more
* Exchange Clients viewpoint, exchanger, rews, rexchange, and ews-api
* Forum Systems forem, Altered beast, thredded, forum_monster, and engagecsm
* Inline CSS for E-Mail premailer, Roadie, mail_style, inline-style, premailer-rails3, and 4 more
* IRC Bots Cinch, Autumn, Isaac, Rbot, Summer, and 7 more
* Content Management & Blogging
* Blog Engines Octopress, Publify, Toto, blogit, Serious, and 2 more
* Content Management Refinery CMS, BrowserCMS, Locomotive, Radiant, Comfortable Mexican Sofa, and 22 more
* Static Website Generation Jekyll, Middleman, high_voltage, Nanoc, stasis, and 13 more
* Wiki Apps Gollum, Git-wiki, Instiki, irwi, Olelo, and 12 more
* CSS
* CSS with Ruby Sass, Compass, sass-rails, bootstrap-sass, twitter-bootstrap-rails, and 14 more
* Font-Face Servers Fontue, Fistface, and Rack::Fontserve
* Data Persistence
* Amazon DynamoDB dynamoid, fake_dynamo, active_dynamodb, and dynoid
* CouchDB Clients Couchrest, CouchRest Model, Couch potato, Couchrest-rails, SimplyStored, and 4 more
* CSV Parsers FasterCSV, smarter_csv, postgres-copy, ccsv, csv_pirate, and 7 more
* Data Migration taps and mysql2psql
* MongoDB Clients Mongoid, Mongo Ruby Driver, Mongomapper, Mongomatic, perpetuity, and 2 more
* Object-relational mapping Active Record, ORM Adapter, Sequel, DataMapper, squeel, and 1 more
* Redis Clients Redis Ruby, Redis Store, Redis Objects, Ohm, redis_orm, and 2 more
* SQL Database Adapters pg, mysql2, sqlite3, mysql, sqlite3-ruby, and 8 more
* Developer Tools
* Benchmarking method_profiler, rbench, bench_press, better-benchmark, Tach, and 2 more
* CLI Option Parsers highline, Slop, cocaine, mixlib-cli, Trollop, and 17 more
* CLI Progress Bars ruby-progressbar, ProgressBar, progress_bar, powerbar, progress, and 4 more
* Concurrent Processing EventMachine, Celluloid, Cool.io, dataflow, workers, and 2 more
* Configuration Management dotenv, settingslogic, Figaro, dotenv-rails, configuration, and 31 more
* Deprecation Tools Deprecated and Structured Warnings
* Gem and Library Inspection open_gem, qwandry, and gemedit
* Gem Creation Hoe, Jeweler, enginex, Echoe, Newgem, and 10 more
* git Tools Grit, githug, Ruby/Git, rugged, gitolite, and 5 more
* GUI Frameworks shoes, FXRuby, Ruby/GTK2, qtbindings, wxRuby, and 2 more
* irb Alternatives Pry and ripl
* irb Tools Dotfiles, Awesome print, Hirb, wirble, pry-rails, and 16 more
* Presentation Software Showoff, CSSS, CoderDeck, Slidedown, Jquery-presentation, and 2 more
* Project Management gitlabhq, Redmine, Teambox, fulcrum, ChiliProject, and 7 more
* Ruby Core Extensions Active Support, Hashie, extlib, hamster, Facets, and 12 more
* Ruby Version Management rbenv, RVM, ruby-build, chruby, Pik, and 3 more
* Scripting Frameworks Rake, Thor, main, Boson, and Sake
* Terminal Coloring term-ansicolor, ansi, colored, colorize, Rainbow, and 2 more
* Text Editors in Ruby Redcar, Ruco, Arcadia, Diakonos, and Ruber
* Documentation Tools
* Documentation Generators RDoc, Yard, Sdoc, DocumentUp, Rocco, and 9 more
* Gem Doc Viewers Bdoc, Sinatra-rubygems, Docbox, and Gembox
* Documents & Reports
* PDF Generation Prawn, Pdfkit, Wicked pdf, Wkhtmltopdf, Prawnto, and 12 more
* PDF Processing pdf-reader, pdf_info, and stevedore
* Reports & Spreadsheets spreadsheet, axlsx, roo, Ruport, google-spreadsheet-ruby, and 23 more
* E-Commerce and Payments
* Online Shops Spree, RoR eCommerce, Invoicing, Shippinglogic, nimbleshop, and 2 more
* Payments Active Merchant, braintree, Stripe, paypal_adaptive, paypal-express, and 11 more
* Subscription Management Freemium, jackpot, fastspring-saasy, SubscriptionFu, and subly
* Fun
* Game libraries Gosu, Chingu, gioco, Gamebox, ray, and 8 more
* Music & MIDI Archaeopteryx, Jazztoolbox, unimidi, Midiator, Midilib, and 8 more
* Graphics
* Graphing Lazy high charts, Googlecharts, Gruff, Open flash chart, Tufte-graph, and 15 more
* Image Processing chunky_png, RMagick, MiniMagick, Image science, image_sorcery, and 6 more
* QR Codes rqrcode, rqrcode-rails3, rqrcode_png, zxing, zbar, and 5 more
* Visualizing Data Raphael, ruby-graphviz, and Ruby-processing
* HTML & Markup
* Breadcrumb Builders breadcrumbs_on_rails, crummy, gretel, breadcrumbs, ariane, and 2 more
* Form Builders Simple Form, Formtastic, nested_form, cocoon, twitter_bootstrap_form_for, and 7 more
* Markup processors Markup, Redcarpet, RedCloth, vkhater-redcarpet, Rdiscount, and 9 more
* Microformats Mofo, Microformats helper, Prism, and html-schema
* Rails Menu Builders Simple-navigation, tabs_on_rails, Semantic-menu, Navigasmic, active_link_to, and 11 more
* Rails Wizards Wicked, Actsaswizard, Wizardly, Wizard, Partially valid, and 1 more
* Syntax Highlighting coderay, rouge, Albino, Jquery-syntax, Harsh, and 9 more
* Table Builders datagrid, wice_grid, tabletastic, table_cloth, table_for_collection, and 8 more
* Template Engines erubis, Tilt, Haml, Slim, Liquid, and 16 more
* JavaScript
* JavaScript Runtimes ExecJS and therubyracer
* JavaScript Testing Jasmine, Testswarm, Blue-ridge, konacha, Evergreen, and 8 more
* JavaScript Tools Sprockets, Uglifier, coffee-script, gon, opal, and 17 more
* Prototype Replacements Jrails, Jquery-ui-rails-helpers, Right-rails, and Yui on rails
* Rails In-Place Editing Rest in place, BestInPlace, Jrails in place editing, on_the_spot, Better-edit-in-place, and 10 more
* Maintenance & Monitoring
* App Instrumentation New Relic RPM, dashing, better_errors, fnordmetric, bullet, and 20 more
* Exception Notification Errbit, Airbrake, Exception notification, Exceptional, Honeybadger, and 8 more
* Log Analysis logstash, Graylog2, request-log-analyzer, central_logger, ntail, and 1 more
* Logging log4r, Logging, gelf, yell, mongodb_logger, and 8 more
* Maintenance Mode turnout and rack-maintenance
* Server Monitoring God, Bluepill, amon, sensu, Outpost, and 9 more
* Package & Dependency Management
* Bundler Tools rubygems-bundler, Appraisal, guard-bundler, spitball, noexec, and 1 more
* Dependency Management Bundler, berkshelf, librarian, Braid, Isolate, and 10 more
* Gem Hosting geminabox, stickler, and gemfury
* Packaging Systems Rubygems, Rip, Rpg, Coral, and SlimGems
* Packaging to Executables Ocra, releasy, Crate, and Rubyscript2exe
* Provision, Deploy & Host
* Amazon Web Services Fog, aws-sdk, Aws-s3, RightAWS, Amazon-ec2, and 7 more
* Asset Distribution asset_sync, Jammit-S3, cloudfront_asset_host, and asset_hash
* Asset Management Jammit, Asset packager, AssetHat, Bundle-fu, Smurf, and 9 more
* Backups Backup, Astrails-Safe, Backup fu, db2fog, Db2s3, and 6 more
* Continuous Integration Travis, Cruisecontrol.rb, Cijoe, Jenkins.rb, Integrity, and 8 more
* Deployment Automation Capistrano, Heroku, mina, Moonshine, git-deploy, and 21 more
* System Provisioning Vagrant, Chef, Puppet, Babushka, Sprinkle, and 7 more
* Web servers Thin, Unicorn, Passenger, Puma, Pow, and 7 more
* Rails Plugins
* Rails Activity Feeds public_activity, TimelineFu, Pfeed, streama, unread, and 2 more
* Rails Admin Interfaces ActiveAdmin, Rails Admin, ActiveScaffold, Typus, Streamlined, and 11 more
* Rails App Templates rails3-application-templates, rails_apps_composer, Rails-templates, Suspenders, Bigoldrailstemplate, and 10 more
* Rails Class Diagrams rails-erd and railroady
* Rails File Uploads Paperclip, Carrierwave, Attachment fu, Dragonfly, Imagery, and 5 more
* Rails Permalinks & Slugs FriendlyId, Stringex, Babosa, Permalink fu, ObfuscateId, and 10 more
* Rails Presenters Draper, Cells, Apotomo, Active presenter, ActiveDecorator, and 9 more
* Rails Subdomains Subdomain-fu, Subdomain routes, Subdomain account, Sso what, and Submarine
* Recommendation Engines recommendify, recommendable, coletivo, Slope One, and similus
* Reputation Engines activerecord-reputation-system, merit, honor, recognition, and reputation
* State Machines State machine, AASM, Workflow, Transitions, Ruote, and 8 more
* User Messaging Systems mailboxer, rails-messaging, acts-as-messageable, maktoub, inboxes, and 3 more
* Security
* Encryption Attr encrypted, Strongbox, crypt_keeper, symmetric-encryption, Sentry, and 5 more
* LDAP Devise ldap authenticatable, omniauth-ldap, Authlogic ldap, Ruby-net-ldap, ldap-activerecord-gateway, and 3 more
* Rails Authentication Devise, OmniAuth, Authlogic, Restful-authentication, Sorcery, and 13 more
* Rails Authorization Cancan, Declarative authorization, rolify, pundit, Acl9, and 20 more
* Rails Captcha Recaptcha, Negative-captcha, Simple-captcha-mirror, galetahub-simple_captcha, humanizer, and 5 more
* Security Tools brakeman, Loofah, Tarantula, Xss terminate, Rails xss, and 10 more
* Spam Detection Rakismet, Defender, Defensio-ruby, Akismetor, Rdefensio, and 1 more
* Testing
* A/B Testing Vanity, Split, seven_minute_abs, bandit, ABingo, and 5 more
* Acceptance Test Frameworks Cucumber, Steak, Turnip, Spinach, Coulda, and 7 more
* Browser testing Capybara, Webrat, capybara-webkit, poltergeist, Culerity, and 9 more
* Continuous Testing Guard, guard-rspec, Watchr, Autotest, Kicker, and 4 more
* Cucumber Steps email_spec, pickle, aruba, Cucumber Factory, MundoPepino, and 2 more
* Cucumber Tools viewcumber, cucumber-nagios, yard-cucumber, cucumber-sinatra, cuke_sniffer, and 7 more
* Distributed Testing Spork, zeus, Parallel tests, spring, Hydra, and 8 more
* Mocking rspec-mocks, Mocha, RR, mock_redis, Flexmock, and 9 more
* Mocking Web Requests Webmock, VCR, Jquery-mockjax, Fakeweb, Artifice, and 5 more
* Rails Fixture Replacement Factory Girl, Machinist, Fabrication, FixtureBuilder, Object daddy, and 9 more
* Random Data Generation Faker, ffaker, Forgery, Randexp, Random data, and 2 more
* Testing Rails Engines combustion, test_engine, and multiengine
* Test::Unit Extensions Shoulda, Context, Contest, and Pending
* Time Warping Timecop, Delorean, time-warp, time_travel, quantum_leap, and 1 more
* Unit Test Frameworks RSpec, Minitest, test-unit, Bacon, Riot, and 12 more
* Time & Space
* Calendars Event calendar, ri_cal, Calendar helper, icalendar, Weekly builder, and 5 more
* Geocoding & Maps Geocoder, Geokit, gmaps4rails, RGeo, Geokit-rails, and 22 more
* I18n I18n, i18n-js, R18n, http_accept_language, Translate routes, and 35 more
* Natural Language Date Parsing Chronic, Chronic Duration, Nickel, Tickle, kronic, and 2 more
* Recurring Events Ice cube, Recurrence, Schedule fu, Runt, Recurring event, and 4 more
* Web Apps, Services & Interaction
* API Builders Grape, rabl, jbuilder, active_model_serializers, acts_as_api, and 9 more
* API Clients Twitter, koala, fb_graph, Linkedin, youtube_it, and 69 more
* Atom & RSS Feed Parsing Feedzirra, Simple-rss, Feed-normalizer, ratom, rfeedparser, and 13 more
* HTML parsing Nokogiri, Hpricot, Libxml-ruby, Scrubyt, Scrapi, and 2 more
* HTTP clients Rest-client, Httparty, faraday, multipart-post, Excon, and 22 more
* HTTP Pub/Sub websocket, faye, em-websocket, libwebsocket, private_pub, and 3 more
* JSON Parsers json, multi_json, yajl-ruby, json pure, crack, and 2 more
* Multitenancy milia, apartment, acts_as_tenant, multitenant, Acts as restricted subdomain, and 4 more
* Rails Controller Abstractions Inherited resources, DecentExposure, Resource controller, Make resourceful, Resources controller, and 3 more
* SOAP Clients Savon, Handsoap, lolsoap, and Serviceproxy
* Social Network Builders Insoshi, Communityengine, Lovd-by-less, SocialStream, Enginey, and 11 more
* URL Rewriting rack-rewrite, Refraction, redirect, and desviar
* User Agent Detection useragent, browser, mobylette, agent_orange, user-agent, and 7 more
* Web Analytics gattica, gabba, rack-google-analytics, Garb, google-analytics-rails, and 10 more
* Web App Frameworks Ruby on Rails, Rack, Sinatra, Padrino, Cramp, and 17 more
* Web Content Scrapers Pismo, data_miner, metainspector, cobweb, sinew, and 4 more
* XML Mapping nori, Gyoku, Happymapper, Sax-machine, Roxml, and 9 more