How do I use Devise in normal AND API mode

Hi guys,
I want to use Devise for creating users with mobile app via REST API but I also want use it in classic fashion.
So in API I want to return JSON and appropriate HTTP codes. Also I want to issue JWT token for authentication for mobile app.
On web I want normal devise functionality.
How I should structure controllers, router and other stuff? I cant find any good resources about this.
Thank you guys.