Realistically, anything you're already comfortable with will work for that. I would pick Python, at least for a quick prototype. You can start thinking about a

Realistically, anything you're already comfortable with will work for that. I would pick Python, at least for a quick prototype. You can start thinking about an efficient implementation when you've got a defined feature set and are seriously thinking about delivering an actual product. And when that happens you can just use which tech works best for which type of service anyway.