Signal

Signal is a privacy-focused messaging application that provides end-to-end encrypted text messaging, voice calls, and video calls. Developed by the Signal Foundation, it's widely trusted by privacy advocates, journalists, and security-conscious users who need secure communications. The desktop version allows users to sync their conversations across devices while maintaining the same strong encryption standards. Signal is completely free, open-source, and designed so that even Signal itself cannot read your messages or listen to your calls.