1.) Languages : RoR(Rails 2, 3,x, 4,x ) / PHP/ Perl/ Python scripts 2.) Deployment Architecture : Heroku/ Engineyard/ AWS 3.) Ruby gems : Activeadmin, hobo, formtastic, devise, omniauth(for social media), resque, foreman, delayed_job, twitter_bootstrap, breakman, cucumber, rspec, factory_girl,capistrano, dalli, paperclip,prawn, haml, carrierwave, nokogiri, redis, rmagick, sass, jammit, capybara, activemerchant,evenmachine, thinking_sphinx,solr(jsonapi) 4.) Api build : Grape, RABL 5.) CMS/ packages : SPREE for ecommerce, refinerycms for cms.