I've known about Teller for some time now but I have always thought that they seem shady... I don't have an issue with them reverse engineering bank APIs, I jus

I've known about Teller for some time now but I have always thought that they seem shady... I don't have an issue with them reverse engineering bank APIs, I just don't get why, how and to whom they would want to sell that. Any small change in any of these APIs completely ruins it for all of their clients. Not even sure if they have a product or service either but again, also not sure who would want that.