Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Axcrypt - AxCrypt - Password Protect Files With Strong Encryption. AxCrypt is the leading open source file encryption software for Windows.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Windows BitLocker - This topic provides a high-level overview of BitLocker, including a list of system requirements, practical applications, and deprecated features.