Here’s a bit about PayNyms from Samourai wallet.
PayNyms works between acting as an intermediary between to people that know each other in the sake of privacy and frequent payments.
Let’s say person X and person Y are friends but don’t want their transaction between wallets on the block chain.
They can exchange PayNyms contacts between each other. Person X sends Y money. Btc goes from person X wallet to PayNyms, PayNyms then transfers the money to person Y wallet.
This keeps the amount of money person X has private when sending money and no way for person Y to see what address person X has.
It’s also good as they save the contact so you can reuse the contact later and make faster payments.
Samourai also offers segwit addresses and of course function to only operate over TOR.