I'm looking for a relatively secure (and hopefully free) Instant Message service. Any recommendations?
what is wrong with good ol' telegram?
https://telegram.org/https://play.google.com/store/apps/details?id=org.telegram.messenger&hl=enan excerpt from their FAQ:
Q: How secure is Telegram?
Telegram is more secure than mass market messengers like WhatsApp and Line. We are based on the MTProto protocol (see description and advanced FAQ), built upon time-tested algorithms to make security compatible with high-speed delivery and reliability on weak connections. We are continuously working with the community to improve the security of our protocol and clients.
Q: What if I’m more paranoid than your regular user?
We've got you covered. Telegram’s special secret chats use end-to-end encryption, leave no trace on our servers, support self-destructing messages and don’t allow forwarding. On top of this, secret chats are not part of the Telegram cloud and can only be accessed on their devices of origin.