SigmaVPN is described as 'Tunnels made simple.SigmaVPN is simple, light-weight and modular VPN software for UNIX systems, deploying the NaCl encryption library. It's easy to configure, has low overheads and is reliable' and is an app in the Security & Privacy category. There are three alternatives to SigmaVPN for a variety of platforms, including Linux, Mac, Windows, Android and Chrome OS. The best alternative is sshuttle, which is both free and Open Source. Other great apps like SigmaVPN are OpenVPN Finder (Free, Open Source) and SlickVPN (Paid).
sshuttle: where transparent proxy meets VPN meets ssh sshuttle is the only program that solves the following common case: Your client machine (or router) is Linux, FreeBSD, or MacOS. You have access to a remote network via ssh.
This simple tool finds free OpenVPN servers for you and allow you to download the OVPN config file. The extension is written on top of VPN Gate Academic Experiment Project that is an online service as an academic research at Graduate School of University of Tsukuba, Japan.