Spanning is described as 'Cloud backup for Google Apps, Office 365, and Salesforce' and is a Online Backup Tool in the Backup & Sync category. There are more than 10 alternatives to Spanning, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and iPhone. The best alternative is MailStore. It's not free, so if you're looking for a free alternative, you could try Tumblr Backup or Gmail Backup. Other great sites and apps similar to Spanning are Backupify (Paid), Keepit (Paid), SpinBackup (Free Personal) and CloudAlly (Paid).
Backupify is the only online data backup and storage provider that enables users to backup their cloud accounts seamlessly to the Amazon S3 cloud, which has a great security and data duplication policy.
A software company specializing in Cloud-to-Cloud data backup and recovery. Deriving from +20 year experience in building best-in-class data protection and hosting services, Keepit is pioneering the way to secure and protect cloud data at scale.
SpinBackup is a cloud backup service, available for Google Apps which protects your data from the most common causes of data loss. It provides daily automatic backups for Gmail, Drive, Picasa and Calendar.