languages

 rubyonrails
 css/html
JavaScript

databases

pg

another gem

devise

frontend

bootstrap-sass

find users by name of town(for find new friends and mark photos by places)

gmaps4rails
geocoder

upload files on server(for project like instagram)

carrierwave
paperclip

behaivor process

sidekiq
redis
also you can find work with smtp (1-st like a main process(after registration on input mail arrived message) ,2-nd like a behaivor
(greetings with birthday)