There's a lot of banks in various countries whose standard “payment API” is uploading a CSV file with a list of account numbers to an FTPS or SFTP server nightly. And guess what happens if you upload the file twice by accident…
I would be more than happy if they just use FTPS/SFTP. I've had enough nightmare working with few that require proprietary Managed File Transfer software (aka MFT) e.g. HULFT, AS1/AS2/AS3 clients.
