While we recommend using Duplicati for performing backups to Cloud Object Storage (S3) on Windows, the tool does not offer a good way to simple list and explore the remote storage. The following Windows applications will provide access to list, explore, and interact with Cloud Object Storage (S3).

ExpanDrive - http://www.expandrive.com/

S3Express - http://www.s3express.com/ (Windows Command line only. No Gui) 

CyberDuck - https://cyberduck.io/?l=en

MountainDuck - https://mountainduck.io/ (From the same company as Cyberduck, but allows COS (S3) to mounted as a Windows Drive)