tinc is a Virtual Private Network (VPN) daemon that uses tunneling and encryption to create a secure private network between multiple hosts on the Internet. This tunneling allows VPN sites to share information with each other over the Internet without exposing any information.
GNUnet is a framework for secure and anonymous peer-to-peer networking that does not use any centralized or otherwise trusted services. Currently, the framework offers censorship-resistant file-sharing, messaging, VPN, GNS (a decentralized version of DNS), and much more. GNUnet is currently developed by a worldwide group of independent free software developers. GNUnet is a GNU package (http://www.gnu.org/).
Shadowsocks client build with ElectronJS and shadowsocks-libev. Supports Windows and MacOS, but not yet Linux.