Amex plans an invoice and payment system with a smart contract that records merchant reputation. Competition remains tight: apart from Visa and Mastercard, American Express (Amex) is now filing another patent for a blockchain-based payment system. According to their patent application, they are building what seems to be an automated invoice system where users can send a request for payment from another user, which may either be approved or declined by the system depending on risk, and update wallet balances based on successful transactions. \u201cA system, method, and computer readable medium (collectively, the \u2018system\u2019) is disclosed for a payment network using a blockchain-based ledger that is configured to execute payment transactions in response to blockchain requests. The system may prepare a request to complete a transaction from an account associated with a payer digital wallet for entry on a blockchain. The request may include an amount and payee address associated with a payee digital wallet. The system may also send the request to the blockchain using a blockchain interface. The system may approve or decline the request. The system may further adjust a balance of the payer or a balance of the payee to reflect approval of the request. The adjustment may include writing the transaction to the blockchain,\u201d they wrote in the document. Based on details of the new patent application, Amex is looking to build this for mobile and any IoT devices, with \u201cpush notifications\u201d being part of the plan. Smart contracts are also employed and the system would supposedly enable a public feedback system between merchants and customers, in what they referred to as a \u201creputation ledger.\u201d This would allow customers and merchants to leave feedback on the transaction within a certain amount of time, and these records may be publicly verifiable, helping users build up a digital reputation score which may be used to assess risk. This isn\u2019t the only patent application Amex filed in a year. They also filed another one for a rewards system last year. At the same time, Visa and Mastercard are also competing, with other traditional banking giants also in on the race. Just yesterday, the Royal Bank of Canada filed an application for a patent on a blockchain-based credit rating system that would help them automate loan approvals through a more comprehensive and transparent background check of borrower history.