Starling in the UK already supports that (for individual, mere-mortal customers) if you are sending money to an existing payee. There is at least a couple of fi

Starling in the UK already supports that (for individual, mere-mortal customers) if you are sending money to an existing payee. There is at least a couple of fintech startups that offer sending money (or even full-blown all-digital bank accounts) using a HTTP API call if you're a business.