The only app that matters this year is Signal
For the uninitiated, Signal is a free and secure messaging application that allows for encrypted texts, phone calls, and video chats between users. That's basically it. Sure, it has a ton of neat features (like disappearing messages), but a big part of what makes it so important is just how simple it is.
If you can use iMessage, you can use Signal. If you can figure out how to send a text message, you can figure out Signal.
And that's the way it should be. With Signal, the private way to communicate is also the easy and free one. No more mucking about with PGP, and no more wondering just who, exactly, is reading your messages.
"There are no ads, no affiliate marketers, no creepy tracking," Whisper Systems explains on its website. "Just open technology for a fast, simple, and secure messaging experience."
The app is available for both Android and iOS, and even has a desktop version.