A gem to find out issuer of the credit card just by entering the Card Number. Currently supports..

Add this line to your application's Gemfile:

gem 'cc_issuer'

And then execute:

$ bundle install

OR install it yourself as:

$ gem install cc_issuer

require 'cc_issuer'
'4444 4444 4444 4444'.cci?   # => Visa

Where, 4444 4444 4444 4444 is to be replaced by your Card Number

require 'cc_issuer'
'4444444444444444'.cci?   # => Visa

require 'cc_issuer'
'4444-4444-4444-4444'.cci?   # => Visa

Where, cci? refers to Credit Card Issuer?

require 'cc_issuer'
'4444-4444-4444-4444'.visa?   # => true

require 'cc_issuer'
'4444-4444-4444-4444'.maestro?   # => false

Where, 4444-4444-4444-4444 is to be replaced by your Card Number

The gem is available as open source under the terms of the MIT License.