lnurl is a protocol for communication between Lightning wallets and third-party services. It simplifies complicated common flows into standard subprotocols carried on between the user wallet and the service over simple HTTP JSON calls, leveraging the fact that the third-party services have the luxury of offering an https:// endpoint the user wallet can freely call.

- Credit: https://telegra.ph/lnurl-a-protocol-for-seamless-interaction-between-services-and-Lightning-wallets-08-19

Specifications:

https://github.com/fiatjaf/lnurl-rfc