Academia.edu - a platform to share papers
https://www.academia.edu/

German Federation of Female Academics
http://www.dab-ev.org/

German Association of University Professors and Lecturers
https://www.hochschulverband.de/english.html#_

Eurodoc - The European Council of Doctoral Candidates and Junior Researchers
http://www.eurodoc.net

Junge Akademie - academy of academics worldwide
https://www.diejungeakademie.de/en/home/

Kisswin - communication and information platform "young scientists"
http://www.kisswin.de/

Promovierenden Initiative - association of graduate scholarship holders (in German only)
http://www.promovierenden-initiative.de/

ResearchGate - Professional Network for Scientists and Researchers
http://www.researchgate.net/

Thesis - interdisciplinary network for PhD students and postdocs (in German only)
http://www.thesis.de/

UniWiND - German University Association of Advanced Graduate Training
http://www.uniwind.org/about-us/