I'm looking for something commercial that would prevent competitors from getting all the user data from my service.
But at the same time, I don't want to put major limitations on what users can do with their data -- even if it is obtained by copying/modifying data from others.
If you're trying to stop automated scraping of your data, then limit the access rate per IP. That won't really help things since someone can just tell the script to slow down to the pace of a normal user.
If a user can access unauthenticated data, so can a computer.
But at the same time, I don't want to put major limitations on what users can do with their data -- even if it is obtained by copying/modifying data from others.