This talk shows how to create a membership site that can be used for production in 20 minutes using Phoenix and phx_gen_auth. With phx_gen_auth, you can develop a membership site or EC site on Elixir and Phoenix in a few minutes to a few days. phx_gen_auth is a library that provides Phoenix with login, member registration, password reminder, and member information changing features, validation checking for these features, and email transmission handlers. However, it requires furthermore following customization of you: Emails Input validations Page display messages Page designs Sign up confirmation I explain with an example of customizing them, based on my much enough development experiences and business background. In addition to the built-in feature, I’ll also explain the points when applying phx_gen_auth to your pages.