Open Source cloud storage software ~ Business Software

Seafile: Easy to setup cloud storage for home users

Seafile is a file hosting cloud storage software to store files. You can synchronized files and data with PC and mobile devices easily or use the server's web interface for managing your data files. There is no limits on data storage space (except for hard disk capacity) or the number of connected clients to your private server (except for CPU/RAM capacity).

Operating system: Cross-platform (written in C and Python) - MS-Windows/Raspberry Pi/Linux private server

Desktop clients: Yes (Windows/Mac OS X/Linux)

Mobile clients: Yes (Android/iPad/iPhone)

Type: File cloud storage and data synchronization

Paid support: Yes via Professional Edition

Licence: GPLv3 (Community Edition)

ownCloud: Dropbox replacement

ownCloud is another very popular file hosting cloud storage software and often described as Dropbox replacement. Just like Dropbox you can synchronizes your files to your private server. Files placed in ownCloud server are accessible via the mobile and desktop apps. You can add external storage to your ownCloud with Dropbox, SWIFT, FTPs, Google Docs, S3, external WebDAV servers and more. Enable the encryption app to encrypt data on external storage for improved security and privacy.

Operating system: Cross-platform (written in PHP & JavaScript) - MS-Windows/Linux private server

Desktop clients: Yes (Windows/Mac OS X/Linux)

Mobile clients: Yes (Android/Apple iOS)

Type: File cloud storage and data synchronization

Paid support: Yes via Enterprise Edition

Licence: AGPLv3

git-annex assistant

The git-annex assistant creates a synchronised folder on each of your OSX and Linux computers, Android devices, removable drives, NAS appliances, and cloud services. You can manage, share, and sync your large files with the power of git and the ease of use of a simple folder you drop files into. Please note that the software is still under heavy development and new features are added regularly.

Operating system: Cross-platform - MS-Windows(beta)/Linux/OS X/FreeBSD/Docker private server

Desktop clients: No (porting)

Mobile clients: Yes (Android)

Type: File cloud storage and data synchronization

Paid support: ???

Licence: GPL version 3

SparkleShare: Easy to use cloud storage with git as a storage backend

It is also a Dropbox clone and very easy to setup. From the project site:SparkleShare creates a special folder on your computer. You can add remotely hosted folders (or "projects") to this folder. These projects will be automatically kept in sync with both the host and all of your peers when someone adds, removes or edits a file.

Operating system: Cross-platform (written in C#) - MS-Windows/Linux/OS X

Desktop clients: Yes ( MS-Windows/Linux/OS X)

Mobile clients: No (Android/iOS on hold)

Type: File and data synchronization

Paid support: ???

Licence: GPL version 3

Syncthing for private, encrypted & authenticated distribution of data

Syncthing is an open-source file synchronization client/server application, written in Go. It replaces proprietary sync and cloud services with something open, trustworthy and decentralized.

Operating system: Cross-platform (written in Go) - Linux, Mac OS X, Microsoft Windows, Android, BSD, Solaris

Desktop clients: Yes (MS-Windows/Linux/OS X/OpeBSD and Unix-like)

Mobile clients: Yes (Android/F-Driod)

Type: File and data synchronization

Paid support: ???

Licence: GPL version 3

Stacksync cloud storage

StackSync is an open-source scalable Personal Cloud that can adapt to the necessities of organizations. It puts a special emphasis on security by encrypting data on the client side before it is sent to the server.