These are direct competitors to Real-Debrid. They offer similar pricing ($3–$5/month) and integrate perfectly with JDownloader 2. They effectively act as a live, updated "premium database" that you legally pay for.
There are various forums and community discussions where users share tips, tricks, and sometimes even accounts or methods to access premium features for free. However, these methods might not always be legitimate or safe. jdownloader 2 premium database free