RetroShare is open source software for encrypted filesharing, serverless email, instant messaging, online chat, and BBS, based on a friend-to-friend network built on GNU Privacy Guard (GPG). Developed by DrBob
License: Open Source
Twister is primarily focused on social networking with a decentralized structure, emphasizing user privacy and anonymity, while RetroShare is a broader platform that offers secure messaging, file sharing, and more, appealing to users looking for a comprehensive communication tool.