What are some alternatives?
When comparing Keybase for Mobile and Signal, you can also consider the following products
MyChat - Secure instant messenger for any network
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
MagicPad - Free, simple, and private, offline text encryption suite.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Wickr - Wickr is a free end-to-end encrypted text, video, picture and voice messenger with full sender...
Riot.im - Open source interoperable collaboration app.