SIGNAL

Like Whatsapp, Signal uses end-to-end encryption, but it takes privacy and security to MI6 levels by not logging any of your messages’ metadata.

Signal can also act as your default SMS messages hub (if you’re still sending those) and, as a crafty bonus, routes calls and texts through your data connection, so you won’t have to use up any of your allowance. It might be tricky to convince your Whatsapp contacts to migrate, but the Android app’s ability to handle unencrypted SMSS means you won’t be completely cut off from non-signallers.