Awesome

OmniAuth ConstantContact

This gem is an OmniAuth 1.0 Strategy for the ConstantContact API

It supports the OmniAuth REST API which uses OAuth 1.0a.

Add the strategy to your Gemfile alongside OmniAuth:

gem 'omniauth'
gem 'omniauth-constantcontact'

Then integrate the strategy into your middleware:

use OmniAuth::Builder do
  provider :constantcontact, ENV['CC_KEY'], ENV['CC_SECRET']
end

In Rails, you'll want to add to the middleware stack:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :constantcontact, ENV['CC_KEY'], ENV['CC_SECRET']
end

You will have to put in your consumer key and secret, which you can find at http://community.constantcontact.com/t5/Documentation/API-Keys/ba-p/25015

For additional information, refer to the OmniAuth wiki.