What you need to know:
Messaging apps can vary significantly in terms of data collection and privacy/security features. In general, most messaging app companies will not directly read your messages however, certain ones will collect information on users called metadata, which can include data such as your contact list, length and time of communications, what device you used and IP address, among other data points. This data can be used in conjunction with other information for targeted advertising.
From a security perspective, apps differ widely in terms of protecting user’s messages in getting in the hands of third parties like governments, internet service providers and hackers. While some apps offer end-to-end encryption by default (which allows only the user to view message) and features like the ability to self-destruct messages, some commonly used services do not, which leave these messages susceptible to getting in the wrong hands.
In fact, even with some of these security protocols in place, some messaging apps have been vulnerable to sophisticated hackers that have lead to high profile incidents. With the private nature of conversations that occur on these apps they have become popular targets for hackers and governments to extract information on users.