TV series API (application programming interface)?

Where do services like "fernsehserien(dot)de," "serienjunkies(dot)de," or "themoviedb(dot)org" get their data about new series? Do they do it all themselves via web scraping, or is there a programming interface or database somewhere where one can query new, future episodes ?

On existing websites on the Internet, you can only filter for future episodes of a single show.

However, I would like a database or service that allows me to search for all broadcast dates of future episodes of several selected series at once and sort them by date. Using SQL queries or something similar, something like this would certainly be possible with a suitable database.

The goal would be to be able to enter all of your favorite series and always have an up-to-date calendar of all new broadcast dates and episodes. Specifically, I'm talking about series from public broadcasters (ARD – extra 3, ZDF – Die Anstalt, etc.).