Wickr is a great option. they have Windows, Mac, Linux, iOS and Android apps. They also have a pro app that can do end to end encrypted voice and video calling

Wickr is a great option. they have Windows, Mac, Linux, iOS and Android apps. They also have a pro app that can do end to end encrypted voice and video calling with forward secrecy. the best part is message timers that cause remote destruction of messages. https://www.wickr.com/ https://www.wickr.com/