Pretty much all online service APIs (Google APIs, Facebook and so on) out there are text-based.

Granted, JSON formatted text, but still absolutelly human readable text.

The reason for that is because it’s agnostic of the machine architectures (stuff like endianess) on both sides.

The really crazy stuff in banking are the old binary protocols (like EDF) from the time when bandwidth was way less than now (so, the early 90s and earlier).