Zmanda Cloud Backup (ZCB) is an online backup software by open source backup company Zmanda which enables users to back up their data to cloud storage. The software uses the Amazon S3 service from Amazon Web Services or Google Cloud Storage as the cloud storage service but also supports private cloud solutions such as OpenStack Swift or Walrus by Eucalyptus via the open source ZCloud API.As of March 2011, the software runs only on Windows platforms.