Let me know if this feels familiar. Your users want to “login with GitHub,” so you install a gem, follow the setup instructions, then pray it never needs maintenance because you have no real idea how OAuth2 works. Let’s fix that. In this article, Diogo Souza shows us the fundamental concepts behind OAuth2 and how to implement them using Devise and Doorkeeper. https://www.honeybadger.io/blog/oauth2-ruby/