Referral for ENS

Make it possible to create an ENS by referral, remunerating projects that encourage the creation of domains through a fee.

This feature stimulates the creation of applications that creates and renew ENS domains, increasing the number of registered names. These platforms would be able to withdraw this fee from the ETHRegisterControler smart contract. I'm already coding this feature and a medium post about will be soon at https://medium.com/blockful