Client software choice
The OpenVPN protocol is not one that is built into the Apple iOS operating system for iPhones, iPads, and iPods. Therefore a client program is required that can handle capturing the traffic you wish to send through the OpenVPN tunnel, and encrypting it and passing it to the OpenVPN server. And of course, the reverse, to decrypt the return traffic. So a client program is required, and there is only one client available that works on standard Apple iOS devices. We do not intend to limit our customers and cause a type of vendor lock-in situation. However, we are currently the only one developing and maintaining an app on this platform.
Official OpenVPN Connect app
On the official Apple App Store, the client you can download and install for free there is called OpenVPN Connect. This program supports only one active VPN tunnel at a time. Trying to connect to two different servers at the same time is a function we did not build into our official OpenVPN Connect app, and it is also not possible because the underlying operating system does not allow this. The OpenVPN Connect app is able to remember multiple different servers, but only one can be active at a time.
To obtain the OpenVPN Connect app, go to the Apple App Store on your Apple iOS device. Look for the words "openvpn connect" and the application will show up in the search results. You can install it from there. Once installed an icon will be placed on your home screen where you can find the app. Once you have it open you can use the Import profile from OpenVPN Access Server option to start the import process. You need to enter the address of your Access Server's web interface here, and click go. You'll be shown the login page and there you can fill in your credentials. A list of downloads for your user account will be shown, and valid selections are the user-locked profile or the auto-login profile, if available. Once imported you can click the plus symbol to finalize the import process. Now you are ready to use the app.
There is no other official OpenVPN client application available on iOS at this time.