[koreth1]

That's an excellent point too. Some payment systems have abysmal technology. The product I worked on was focused on international payments and in a couple cases, the "API" was literally, "Upload a CSV file via FTP, and at some later point, another CSV file might appear on the FTP server with some of the payment results, but if it doesn't, call us because we probably just forgot to upload it."

[nijave]

Batch jobs and (S)FTP. In a bit of a weird twist, back when I worked at Chase, they were innovating on the ancient technology but it was things like "better batch job management/orchestration" and SFTP proxy to route between different servers and centralize key management