Contao Open Source CMS (fka TYPOlight)
Web-based HTML5 Photo Viewer
Software auto-installation builder
Kurisu OS 3.0
Proofreading Software for 20+ Languages
The leading Open Source survey tool
LGSL (Live Game for PHP 5.4-8+: online status for various gameservers
The open content management system for news.
Open Source photo Library Software
Free and open source webmail software
Create and edit SVG graphics directly in ownCloud. Based on svg-edit.