Starting using vali-admin, an Free Bootstrap 4 Admin Template in Rails 5.2
Ruby on Rails, Devise (Users and Admins), Rails Admin, Simple Navigation, Twitter Bootstrap, HAML
Rails Liana for Forest Admin
Rails Admin Settings: App Settings management via RailsAdmin
Rails Admin Import functionality
Framework for creating powerful admin backends with minimal effort in Ruby on Rails.
Rails template application of an admin panel with the AdminLTE theme integrated.