<watch this space, and the night sky!>
API used: G7VRD's public satellite pass API
This API is free to use, without authentication. Required parameters are the desired satellite's NORAD ID (= 25544 for the ISS) and the viewing location's latitude and longitude.
Optional query parameters are minimum elevation at peak (default = 30 degrees), and number of hours for forecast (default = 48, maximum = 72).