Threema is an encrypted instant messaging application for iOS, Android and Windows Phone. Developed by Threema GmbH
License: Commercial
Threema is a paid messaging app that emphasizes privacy and anonymity, requiring no phone number for registration, while ChatSecure is an open-source app that supports multiple protocols and integrates with Tor for enhanced anonymity. Both apps provide strong encryption, but Threema is more user-friendly, whereas ChatSecure may appeal to technically inclined users.