Thanks for your inquiry.
You may find following resources helpful:
Please note that GroupDocs.Annotation is platform independent and a storage-agnostic API, this means that it does not support any specific storage (i.e. Oracle, MS SQL Server and so on). But it provides abstract interface that you can implement, and use for storing data in specific storage. For details about this feature, please visit this article.
GroupDocs.Annotation API permits developers to do collaborators/user management. You can perform following operations:
- Adding Collaborator
- Getting Collaborator
- Updating Collaborator
- Deleting Collaborator
- Managing Collaborator Rights
Learn more about it in this article
Yes, we have developed some sample showcase projects for your ease here which saves annotations in the JSON file. We would also recommend you to try our Modern UI showcase that is more simple, efficient and, user-friendly. Furthermore, these showcase projects are open-source, you may enhance them to any extent or as per your use-case.