The CosyncJWT authentication service is implemented as a SAAS service for MongoDB Realm Developers. The service is free for development apps with less that fifty 50 users. For commercial applications with more than fifty users, the developer must sign up for a developer account at a cost of six dollars $6 per month, and is charged $0.001 per user per month after an initial free 5000 application users.
The CosyncJWT service is not open source, although the company is considering a self-hosted version of CosyncJWT in the future. The CosyncJWT service is licensed under the terms of the Cosync Service Agreement, which can be found here SLA Agreement.