Mycelium has implemented Proof of Payment (BIP120 and BIP121), and I’m really glad they did. It’s one of the most popular wallets out there. Plus, I implemented most of it. I’d like to show you how smooth the user experience can be when PoP is used poperly! If you would like to play with this, please visit my PoP test site. It supports both mainnet and testnet. I’ll show a service I call PayMess. That’s a site where you pay for a message space. You can then update that message space with whatever you want for free whenever you like using PoP. Here we go: