^1Windows/Linux/Mac/iOS/Android/BlackBerry - Supported operating systems for thick client (native binary application), which provide background data transmission and setting services.
^2Personal Encryption - The user needs to manage their own encryption key or password. If they lose it, there is no way to access the data. The service provider cannot access the user's data even if required by the government.[72][73] Backup service providers often claim that no one can access the users data even though they themselves could if forced to do so, so entries claiming support of this feature should always have a supporting reference. If the backup service has a password recovery or reset mechanism that allows a user to access their data when they lose their password or key, that proves they do not have personal encryption.
L - Pay per computer. Additional fee for storage over a threshold.
U - Pay per computer. Storage per computer is unlimited.
M - Pay per unit of storage, but unlimited computers may share that storage.
B - Bandwidth capping or limits are used on accounts.
^4Net drive - a network drive acts as a regular computer drive, but is hosted remotely on a file server. Some common protocols used (FTP, SMB, NAS,...)
^5P2P storage - data spread over many computers based on peer-to-peer net advantages.
^6Sync - Synchronization between computers, and/or mobile devices (PDA, MDA,...)
^11 Whether the desktop client (if available) can detect and upload changes without scanning all files.
^12 Many backup services offer a limited free plan, often for personal use. Often it is possible to increase the free backup limit through coupons, referrals, or other means that are not included in this column. This column also does not include free trials that are only available for a limited period of time.
^13External hard drive support - Can refer to an alternate backup destination or whether the service can back up external drives.
^14 Hybrid Online Backup works by storing data to local disk so that the backup can be captured at high speed, and then either the backup software or a D2D2C (Disk to Disk to Cloud) appliance encrypts and transmits data to a service provider. Recent backups are retained locally, to speed data recovery operations.
^15 Bitcasa encrypts each file with a key derived from that file, so a file can be decrypted only if you already have (or have had) the decrypted version. Therefore bitcasa cannot decrypt arbirary files, but they could e.g. remove a specific requested file or log which users access a specific requested file. There also is a learn-the-remaining-information attack possible.[74][75]
Comments
Acronis
Up to 5PCs, always incremental backups, remote access from the web
AltDrive
Data de-duplication; block-level incremental; Unlimited offering. Home (1-3 computers) or Biz service (1-1000 computers). Client-side encryption.
ASUS WebStorage
Auto upload on designated folder, Auto backup Capabilities, Cross platform file access of upload and sharing - iOS, Android, Windows Marketplace, OSX, Ubuntu, Linux, Windows Store (Windows OS) also any compatible browser. 5GB of free data. Upload limit for each file 500MB on free account. Daily file sharing limit 500MB on free account. Free account will only allow one computer to be able to backup.
Backblaze
Data de-duplication; block-level incremental
Barracuda Backup Service
Data de-duplication; real-time hybrid onsite/offsite data back-up
BullGuard Backup
5PC/license, fast upload speeds, mobile access, encrypted transfer and storage, password-protected settings, free 24/7 support
Carbonite
Block-level incremental, Home or Pro Editions. iPhone/ Black berry/ Android App available To remotely access data from the online backup (For Pro: Users of the computer which are backed up, Not available for the Administrator of the Pro). Can manually select files to upload that are larger than 4 GB.
Crashplan
Unlimited destinations. Data de-duplication; block-level incremental. Can run server-free, exchanging backup space with friends and family.
Cloud storage that is specifically designed for the Mac ecosystem. Also allows users to store files exclusively in the cloud for seamless access on any computer or mobile device.
Diino
iPhone/Android app available.
Dropbox
Data de-duplication, delta sync, iPhone/Android/Blackberry app available.
Dropmysite
website backup, database backup, SFTP support, free up to 2GB.
Egnyte
Delta sync, Google Docs sync, user and group management
ElephantDrive
Auto-transfer from defunct Xdrive.
Fabrik Ultimate
Backup Block-level incremental backups, Encryption: 128 bits standard, 448 bits optional, limited account of up to 3 GB is free. Acquired by Hitachi. According to their tech support, their offering is a branded version of Memopal.
FilesAnywhere
Mark Cuban acquired minority interest in 2006. Android, iOS, BlackBerry Apps available. Dedicated server options available. CoolBackup software used for Backup/Sync.
F-Secure
[Steek acquired by F-Secure July 2009]
Humyo
Humyo was acquired by Trend Micro and will become part of Trend Micro SafeSync. Humyo no longer accepts new clients.
IASO Backup
Advanced data reduction technology. Data de-duplication mechanism. High level of scalability and cost effectiveness.
Initial seed via a MiMedia-owned external hard drive available (no extra cost, shipping included).
Mozy
Data de-duplication; block-level incremental. "Mozy Data Shuttle" physical seeding service available for extra fee.
SpiderOak
Data de-duplication."Zero Knowledge" encryption.
StoreGrid Cloud
Byte-level Incremental backup, local backup, Disk Image Backup - BMR and physical seeding.
Syncplicity
Google Docs sync, Central Management with Business Console
TaniBackup (Cheap Backup)
Up to 10 TB per standard package. Extendable to over 300 TB per single account. Access via SMB/CIFS or SSH (including sftp, scp, rsync and so on). 100 GB for just $2 per month.
Tarsnap
Client source available; data de-duplication; block-level incremental.
Ubuntu One
GPL client
Unitrends Vault2Cloud
Data de-duplication; hybrid on- & off-premise data backup; physical seeding
UpdateStar Online Backup
Data de-duplication; block-level incremental
Usenet backup
Is the method of storing backup data on the usenet.[76]
Windows Live Mesh
replaces windows live sync and windows live folder
Wuala
Client-side encryption, Wuala does not have access to the data.
Zetta Enterprise-grade Online Backup
Supports Linux, Mac OS, and Windows, high speed WAN optimization, SAS 70 certified datacenters
Zmanda Cloud Backup
Available in German and Japanese languages, supports MS SQL Server, MS Exchange, SharePoint, MySQL Database, System State, Oracle
Versioning
Any changes can be undone, and files can be undeleted.
Acronis
Supports detailed history of changes to files with browsing by date or version number.
AltDrive
Old versions of files are kept for 30 days. Biz customers choose their retention policy of 30 days to 7 years to forever.
Backblaze
Old versions of files are kept for 30 days.
Carbonite
Keeps old versions for up to three months. It keeps one version for each day of the past week, one version for each of the previous three weeks, and one version for each of the previous two months that the file has been backed up.
Crashplan
Options: All, or staged (daily, then weekly, etc.).
Dolly Drive
Yes. Keeps unlimited versions of files.
Dropbox
No version history kept in free account as of 2012, but discrete files deleted can be undeleted.
Dropmysite
Provides incremental backups with the ability to download every snapshot.
ElephantDrive
Old versions of files are kept for 30 days.
IASO Backup
All versions of files can be kept for different periods of time, starting from 1 month to 1 year or more.
PowerFolder
Five versions are kept online. In the client it is configurable how many versions to store locally.
SOS Online Backup
All versions are kept. Only the largest counts towards the storage limit.
SpiderOak
All versions are kept. All files can be undeleted.
SugarSync
Five versions are kept. Only the most recent version of each of existing files as well as deleted files count towards the storage limit.
Wuala
Ten versions are kept. Only the most recent counts towards the storage limit.
Zetta Enterprise-grade Online Backup
All versions are kept. All files can be undeleted.
^What is max file size for upload?"There is no maximum file size limit for adding the file through the SugarSync Manager application. However, there is a 100MB limit for files being uploaded through the SugarSync website."
^Even though UpdateStar allows you to manage your own private key, they also have an Encryption Key Recovery Service. How that exactly works is not clear from the website.