To tackle privacy issues, app developers have come up with encrypted messaging solutions. With end-to-end encryption, your sent message becomes completely illegible to digital snoops or the government. This is a common practice by most messaging apps today, some of which you still need to opt-in to, and some are automatically enabled. A level above this form of security are apps that are serverless. Which means no one in between, not even the app owners can have access to your chat history. No third party can demand access to user information through a back door if requested.
Android still tends to be the default platform for secure messaging apps, with many options and different levels of security to choose from.
Here are the different option you have for secure messengers for Android to download: Zangi, Wickr Me, WhatsApp, Viber, Signal, Threema and Wire.
Source: https://zangi.com/news/en/secure-messaging-apps-for-android/