Pritunl Client is described as 'Simple OpenVPN Client and GUI. Additional integration available when connecting to a Pritunl server' and is an app in the Security & Privacy category. There are three alternatives to Pritunl Client for a variety of platforms, including Windows, Android, iPhone, Linux and Mac. The best alternative is OpenVPN, which is both free and Open Source. Other great apps like Pritunl Client are WireGuard (Free, Open Source) and Securepoint VPN Client (Free, Open Source).
WireGuard is an extremely simple yet fast and modern VPN that utilizes state-of-the-art cryptography. It aims to be faster, simpler, leaner, and more useful than IPSec, while avoiding the massive headache. It intends to be considerably more performant than OpenVPN.