Threema. Secure and private Me ssenger – one of the best messengers in the field of security of negotiations between users. Developers use proprietary end-to-end encryption to ensure that any participant knows for sure that confidential information will not fall into the wrong hands. But the program is also a great and friendly way for the most convenient and lightning-fast communication. Voice calls, sending files, posting videos, creating group chats, syncing contacts, full anonymous communication and much more have made the program so popular among users.