Anonymous users are limited to 20 calls per 10 minutes and 50 calls per day; while authenticated users have a limit of 300 calls per 10 seconds, 2k calls per 10 minutes and 50k calls per day. As for the premium users, they have a limit of 5k calls per 10 minutes and a limit of 720k calls per day. They are also limited to 10 bulk downloads per hour.