Nostr Wallet Connect. It was originally developed open source by nostr:nprofile1qqsyv47lazt9h6ycp2fsw270khje5egjgsrdkrupjg27u796g7f5k0spzemhxue69uhk2er9dchxummnw3ezumrpdejz7qgwwaehxw309ahx7uewd3hkctcprdmhxue69uhkummnw3ez6vfwde3x7tnpdenkzmnf9e3k75xqss4. It allows your lightning wallet to connect to any compatible application by using Nostr relays as the government.

A compatible wallet will provide a "connection string" which has all the information another compatible app needs in order to communicate with it. This connection string just needs to be pasted into the app you want your wallet connected to.