Tumblr Backup is described as 'lets you easily backup your blogs contents, theme, description and more, to your computer' and is an app in the Backup & Sync category. There are four alternatives to Tumblr Backup for Online / Web-based, Android, iPad and iPhone. The best alternative is Backupify. Other great apps like Tumblr Backup are Spanning (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.
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.