These VPN clients are built on the OpenVPN protocol, which is itself open source, has been audited several times, and is generally considered to be the most secure VPN protocol available.

Nord has the most features of any VPN on the market, with tools that will appeal to power users as well as an easy-to-use Android app that is intuitive and straightforward even for beginners.

Kaspersky has fixed a bug in their Kaspersky VPN app for Android that leaked the computer's configured DNS server while using a VPN connection.