IMDb

The  Internet Movie Database  or  IMDb  is a large film and television database and silo that allows for rating content, reading and writing reviews, creating watchlists, and adding media checkins among other functionalities.

Export Data
IMDb previously had RSS feeds for portions of personal data including lists and what they call checkins (see instead watches), but no longer supports that functionality (though as of 2020-01-16 their help page indicates that they do).

Most pieces of functionality on the site that pertain to one's personal data has an "export this list" link at the bottom right of those pages to allow one to export their data as a .csv file.

As of 2020-01-16 IMDb doesn't seem to have functionality for exporting reviews.

Letterboxd, a competing silo, has a good page that outlines how to export your ratings, checkins, watchlist, and lists from IMDb.com (as well as the ability to upload it to their site in a silo-to-silo syndication fashion.

Your own movie database in 5 minutes with IMDb API and Perl