FBI's ability to legally access secure messaging app content and metadata [pdf]
Check the difference between Telegram and WhatsApp.<p>Add to this the fact that WhatsApp<p>- uploads messages unencrypted to Google if you or someone you chat with enable backups<p>- and send all your metadata to Facebook.<p>Then remember how many people here have tried to tell us that Telegram is unusable abd WhatsApp is the bees knees.<p>Then think twice before taking security advice from such people again.<p>PS: as usual, if your life depends on it I recommend using Signal, and also being generally careful. For post card messaging use whatever makes you happy (except WhatsApp ;-)