ownCloud gives you freedom and control over your own data.
A personal cloud which runs on your own server.

http://ownCloud.org

Installation instructions: http://doc.owncloud.org/server/5.0/developer_manual/app/gettingstarted.html
Contribution Guidelines: http://owncloud.org/dev/contribute/

Source code: https://github.com/owncloud
Mailing list: https://mail.kde.org/mailman/listinfo/owncloud
IRC channel: https://webchat.freenode.net/?channels=owncloud
Diaspora: https://joindiaspora.com/u/owncloud
Identi.ca: https://identi.ca/owncloud

Important notice on translations:
Please submit translations via Transifex:
https://www.transifex.com/projects/p/owncloud/

For more detailed information about translations:
http://owncloud.org/dev/translation/