For basic tasks, such as configuring routine backup or shared hosting for large files, there are GUI tools for accessing S3 API compatible object storage.
Cyberduck is a popular, open-source, and easy to use FTP client that is also capable of calculating the correct authorization signatures needed to connect to IBM COS. Cyberduck can be downloaded from cyberduck.io/.
Cloudberry is a flexible backup utility that allows users to back up some or all of a local filesystem to an S3 API compatible object storage system. It can be configured to be run either manually or scheduled based on need, and can backup different directories to different buckets if needed. Cloudberry can be downloaded from cloudberrylab.com.