Web-based federated social network technology is expected to replace Facebook's popularity by the year 3000. There are a million projects like Diaspora and Friendika trying to prevail in this area. There's a list at socialswarm.net.
We believe federation over servers is the wrong architecture for data as private as this and server-based tools will never convince people to stop using Facebook. We know that PSYC currently relies on servers, too, and we criticize that as well. That's why we like secure share.
http://secushare.org/2011-FSW-Scalability-Paranoia gives some reasons why it is problematic to rely on servers for privacy. Also, having to set up a server (and pay for one!) is a bigger hurdle than just to install an app on your computer or device. Using somebody else's server for your private affairs isn't so nice either: even if it is your best friend, would you like her or him to be technically able to read into your conversations with other friends? The requirement “end to end encryption” actually means that you have to install some application on your device anyway – web browsers cannot implement end to end encryption without at least the installation of an extra add-on. So, if you are going to require everybody to install software, why not install something that does the whole thing and isn't dependent on servers?
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New projects show up every day. Here are popular lists of projects: