Today WhatsApp is the most popular messenger in the world.
Many people ask question :
Is WhatsApp secure?
And that is what WhatsApp support team answer:
“WhatsApp communication between your phone and our server is encrypted.
Even though data sent through our app is encrypted, please remember that if your phone or your friend’s phone is being used by someone else, it may be possible for them to read your WhatsApp messages. Please be aware of who has physical access to your phone.”
However, if you are posting some messages to public groups, you have to be very accurate because in some countries you can be arrested for posting inappropriate content.
If you want to be 100% safe and secure it is better to use vpn.