Joyent Triton Object Storage

Triton Object Storage (previously named Manta Storage) by Joyent is now supported in Cyberduck 6.3 and Mountain Duck 2.2. Make sure to install the connection profile.

Their storage backend implementation is open source.

All the pieces required to deploy and operate your own Manta are open source

Triton Object storage touts itself as

Proven at production scale, Triton Object Storage delivers replication, clustering, failover, and backup and recovery capabilites. Robust security is built in, including object level security and access, deep role based access control, and client SSH and data encryption.

Update: Read more about the Triton Object Storage and Cyberduck on the Joyent Blog.