I18n

Devise uses flash messages with I18n, in conjunction with the flash keys :notice and :alert. To customize your app, you can set up your locale file:

en:
  devise:
    sessions:
      signed_in: 'Signed in successfully.'

You can also create distinct messages based on the resource you've configured using the singular name given in routes:

en:
  devise:
    sessions:
      user:
        signed_in: 'Welcome user, you are signed in.'
      admin:
        signed_in: 'Hello admin!'

The Devise mailer uses a similar pattern to create subject messages:

en:
  devise:
    mailer:
      confirmation_instructions:
        subject: 'Hello everybody!'
        user_subject: 'Hello User! Please confirm your email'
      reset_password_instructions:
        subject: 'Reset instructions'

Take a look at our locale file to check all available messages. You may also be interested in one of the many translations that are available on our wiki:

https://github.com/plataformatec/devise/wiki/I18n

Caution: Devise Controllers inherit from ApplicationController. If your app uses multiple locales, you should be sure to set I18n.locale in ApplicationController.