my most used Gems for Rails API

gemfile.rb

source 'https://rubygems.org'

gem 'rails', '4.2.3'

gem 'active_model_serializers'           # Serialize json response
gem 'delayed_job_active_record'          # Asynchronous priority queue system
gem 'figaro'                             # For setting environment variables
gem 'kaminari'                           # for pagination
gem 'newrelic_rpm'                       # Monitor
gem 'pg'                                 # Posgrees Database
gem 'pundit'                             # Authorization
gem 'rack-cors', require: 'rack/cors'    # CORS
gem 'signal'                             # Observer

# Authentication
gem 'devise_token_auth'
gem 'omniauth'
gem 'omniauth-facebook'
gem 'omniauth-google'
gem 'omniauth-linkedin'
gem 'omniauth-twitter'

# Internationalization
gem 'devise-i18n'
gem 'rails-i18n', '~> 4.0.0'

group :development do
  gem 'better_errors'           # Replaces the standard Rails error page
  gem 'brakeman', require: false# Analizes the security of code
  gem 'pry-rails'               # Makes "rails s" command run 'pry' instead.
  gem 'rubocop', require: false # Analizes the hole code for better semantic
  gem 'spring-commands-rspec'   # Rspec with Spring (for faster tests)
  gem 'thin'                    # HTTP server lighter, no setup required
  gem 'annotate'                # Annotate generator
end

group :development, :test do
  gem 'byebug'                  # Debug tool
  gem 'ffaker'                  # A library for generating fake data
  gem 'spring'                  # To make rake/rails tasks command load faster
  gem 'web-console', '~> 2.0'   # Access an IRB console on exception pages
  gem 'factory_girl_rails'      # Fixtures replacement
end

group :test do
  gem 'rspec-rails'                        # Framework for test
  gem 'rspec-collection_matchers'          # Collection for extra rspec matchers
  gem 'shoulda-matchers', require: false   # Extra helpers for rspec
end

group :production do
  gem 'keen'           # Keen IO, Analitics for developer
  gem 'rails_12factor' # Heroku Dependences
  gem 'unicorn'        # HTTP server
end

gem 'sdoc', '~> 0.4.0', group: :doc