Important ruby gem list

To Create admin panel: ActiveAdmin :  rubygem | github Activeadmin-axlsx :    rubygem | github AES encryption / decryption Ruby gem Aescrypt : rubygem | github Mailing Functionality: Letter Opener : rubygem | github Calculate difference between two given time: Time Diff : rubygem | github Time Difference : rubygem | github To check the quality of rails code: Rails best practices ...