No obligation - no credit card needed to try it out.
The only thing you need is a real email address. Kopi has to have somewhere to forward your email to!
If you use single sign-on with a Social login provider (Google, etc.) - Kopi will need permission to read the email address associated with the account.
One touch single sign-on with Facebook / Google / Twitter / Microsoft. Or you can also sign up with a simple email/password.
When you first use Kopi - a simple tutorial will guide you to creating your first forwarder and receiving an example email.