English User Manual: https://en.wikibooks.org/wiki/Goldbug 
COMPILE from source:
https://github.com/textbrowser/spot-on
GoldBug offers for these main functions of E-Mail, Chat, IRC-like Groupchat, Filesharing and Web search multi-encrypted transfers based on asymmetric and also symmetric end-to-end encryption, the user can define. Once you have exchanged your encryption keys with a friend, the usage is very easy.
With many features GoldBug differs from other alternatives.
COMPILE from source:
https://github.com/textbrowser/spot-on
GoldBug offers for these main functions of E-Mail, Chat, IRC-like Groupchat, Filesharing and Web search multi-encrypted transfers based on asymmetric and also symmetric end-to-end encryption, the user can define. Once you have exchanged your encryption keys with a friend, the usage is very easy.
With many features GoldBug differs from other alternatives.