^1 Windows/Linux/Mac/iOS/Android/BlackBerry - Supported operating systems for thick client (native binary application), which provide background data transmission and setting services.
^2 Zero knowledge - 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. 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 zero knowledge.
^3 Secure Key Management - If yes, the user holds and controls of the encryption key. If no, the service provider holds and controls the encryption key.
^4 Payment options/plans:
Limited MB plan - Pay per computer. Additional fee for storage over a threshold.
Unlimited MB plan - Pay per computer. Storage per computer is unlimited.
$/MB plan - Pay per unit of storage, but unlimited computers may share that storage.
^5 Cloud hosted Net Drive - Cloud can serve storage over WebDAV, SMB/CIFS, NFS, AFP or other NAS protocol, allowing files to be streamed from the cloud. A change made to the cloud is immediately accessible to applications on all clients without needing to pre-download (sync) the file in full.
^6 P2P storage - data spread over many computers based on peer-to-peer net advantages.
^7 Sync - Synchronization between computers, and/or mobile devices (PDA, MDA,...)
^8 Public Internet file hosting -
^9 Restore via physical media -
^10 Server location - countries where physical servers are located. Where the data will be located.
^11 Still in Beta version
^12 Whether the desktop client (if available) can detect and upload changes without scanning all files.
^13 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.
^14 External hard drive support - Can refer to an alternate backup destination or whether the service can back up external drives.
^15 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.
^16 Unlimited BW - If bandwidth capping or limits are used on accounts.
Acronis
Up to five PCs, 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, external USB drives, NAS support for Biz customers.
Backblaze
Data de-duplication; block-level incremental.
Barracuda Backup Service
Data de-duplication; real-time hybrid on-site/off-site data back-up.
blaucloud
No User Limit each User get his ownCloud Instance in an encrypted Storage.
BullGuard Backup
5 PC/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/ Blackberry/ 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.
Datashield
High-level encryption, personalized encryption key, shared cloud drive, sync folder functionality .
Datto
Focused on business continuity and total data protection for small and medium businesses. Offers instant virtualization of backed up instances locally or securely in the cloud. Datto maintains its own private cloud with 250+PB of protected data in 9 data-centers.
Dolly Drive
Cloud storage that is specifically designed for the Mac. 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 2 GB.
Egnyte
Delta sync, Google Docs sync, user and group management
ElephantDrive
Auto-transfer from defunct Xdrive.
FilesAnywhere
Mark Cuban acquired minority interest in 2006. Android, iOS, BlackBerry apps available. Dedicated server options available. CoolBackup software used for backup and 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.
ICFiles
Secure File Share Storage. Proprietary license download client. High level security, SOC 2 TYPE II, ISO 27001,27017, 27018, CSA, PCI, HIPAA, CJIS, EU Model Clauses, on request private servers for FISMA and FedRAMP.
IDrive
Proprietary license download client. Automatic Selection. Continuous Data Protection. "Virtual drive" explorer.
Jungle Disk
Proprietary license download client sample code.
KeepVault
Real-time hybrid on-site and offsite data backup.
Memopal
Cross-user de-duplication, delta sync.
MiMedia
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.
Replicalia
Professional Backup for Professional Data.
pCloud
Data de-duplication. Zero Knowledge Privacy with client-side encryption.
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. Extensible to over 300 TB per single account. Access via SMB/CIFS or SSH (including sftp, scp, rsync and so on). 100 GB for $2 per month.
Tarsnap
Client source available; data de-duplication; block-level incremental.
TeamDrive
Store encrypted data on any WebDAV server; supports working offline; files can be commented; built-in support for conflict resolution.
Tencent Cloud
Tencent is offering users 10GB of free cloud storage
Unitrends Vault2Cloud
Data de-duplication; hybrid on- and off-premises 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.
Windows Live Mesh
Replaces windows live sync and windows live folder.
Zetta Enterprise-grade Online Backup
Supports Linux, Mac OS, and Windows, high speed WAN optimization, SAS 70 certified data centers.
Zmanda Cloud Backup
Available in German and Japanese languages, supports MS SQL Server, MS Exchange, SharePoint, MySQL Database, System State, Oracle.
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 60 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.
blaucloud
Keeps old version if versioning app is activated (included in all plans even FREE) until users runs out of storage.
Box
Versioning is included in paid subscription
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. Versioning available for PC computers only; not available for Mac.
Crashplan
Options: All, or staged (daily, then weekly, etc.).
Cubby
All previous versions and deleted files are kept until explicitly removed by the user or the user runs out of space. All deleted files and previous versions count towards the storage limit.
Dolly Drive
Yes. Keeps unlimited versions of files.
Dropbox
By default, Dropbox saves a history of all deleted and earlier versions of files for 30 days for all Dropbox accounts.
Dropmysite
Provides incremental backups with the ability to download every snapshot.
ElephantDrive
Any number of versions can be kept for any amount of time.
Google Drive
Old versions of files are kept for 30 days or 100 revisions. Revisions can be set not to be automatically deleted.
IASO Backup
All versions of files can be kept for different periods of time, starting from 1 month to 1 year or more.
ICFiles
No files are kept after delete, auto delete clears at every 24 hours.
iDrive
Up to 10 old versions of files are kept forever (until explicitly removed).
Mozy
Old version of files are kept for 30 days. Pro 60 days, Enterprise 90 days.
pCloud
Versioning is included for free (30 days) and paid plans (180 days). Deleted files can be restored within the same timeframes.
PowerFolder
Five versions are kept online. In the client it is configurable how many versions to store locally.
SOS Online Backup (Infrascale)
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.
Syncplicity
Old versions of files, as well as deleted files, are kept for 30 days. Configurable for business or enterprise-class services.
TeamDrive
All previous versions are kept and can be restored.
Tresorit
Versioning is included in paid subscription
Zetta Enterprise-grade Online Backup
All versions are kept. All files can be undeleted.
Other features and limitations
Other notable limitations or features.
Baidu Cloud
Must be registered by verified phone first.
Box
Performance degrades after 10,000 files in sync folder. Technical limit of 40,000 files in sync folder. Does not sync .tmp files, Outlook PST files, hidden files (hidden folders are synced), or any file or folder with /*?":<>| in the name.
Dropbox
Performance degrades with more than 300,000 files in sync folder. This is a soft limit.
pCloud
Can exclude certain file types (e.g., .tmp files) with a file type exclusion filter.
Sugarsync
Limited to 80,000 files per top level sync folder. To workaround, you can create multiple syncing folders, but each top level folder is limited to 80k files. Also, Microsoft outlook and Apple iTunes databases are unsupported.
Bitcasa closed its services in February 2017.
Copy was discontinued on May 1, 2016
Dell DataSafe was discontinued on June 11, 2015.
drop.io
Norton Zone was discontinued on July 7, 2014.
Trend Safesync (not included in the table above) is no longer available and existing accounts will be purged on January 31st 2017.
Ubuntu One was discontinued on June 1, 2014.
Windows Live Mesh
Wuala was discontinued on November 15, 2015.
Xdrive
ZumoDrive
PogoPlug, discontinued online backup services September 28, 2016
