Linchpin - I am looking for an extranet for communication with clients

I am looking for an extranet in order to also communicate with clients. Do you have any recommendations for me?

Please take a look at our intranet solution Linchpin which lots of clients are using as an extranet: https://www.linchpin-intranet.de/

Addionally we offer an add-on which includes extranet use cases:
https://info.seibert-media.net/display/DOC/Space+Guardian+for+Confluence+-+User+and+Administration+Guide+1.0

Base for both is Atlassian’s Confuence:
Anmelden -