http://openvpnandroid.com/nordvpn-vs-ipvanish-vs-expressvpn-vs-openvpn/

OpenVPN Connect, the “official” OpenVPN Inc. app, is designed to be user-friendly for VPN users with no technical expertise. It’s not as feature-rich as openvpn for Android, which is geared toward more advanced OpenVPN users.

Openvpn for Android Openvpn for Android, a free and open-source client developed by Arne Schwarzbe, enables you to connect with any VPN service that supports OpenVPN protocol. It’s a great option in the event that your device isn’t compatible with pre-configured “off the shelf” VPN apps that are available in the Google Play Store. The setup process is fairly straightforward. It is as simple as importing your VPN profile files (the config files have an extension of.ovpn) which you can obtain from your provider’s website or by reaching their live chat support team.

After you’ve added your profile, click on the server to connect. Once connected, your Internet traffic is directed through a secure tunnel to the server you’ve selected in the app. You can view the status of your connection and its details on the Status tab. The kill switch is enabled by default. It will shut down your internet connection if the VPN tunnel is cut off.

The application offers a per-app VPN as and an option to be always on that automatically creates an VPN connection whenever the app is opened and keeps it running after your device has gone to sleep or switched networks. However, the latter requires Android 7.0 or higher and will draw more power from your battery than usual.