ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.

Easy Message - Easy Message app comes up with features to help users in effortlessly sending text messages to a phone number, which is not in the contact list.

Enigmail - Security extension to Mozilla Thunderbird and SeaMonkey

Seecrypt - Seecrypt app allows users to do secure voice and conference calls by using advanced encryption features so they can contact their friends, colleagues, and family members without any privacy issues.

Tutanota - Get your encrypted mailbox for free.

Silent Phone - Silent Circle is a secure communications firm offering enterprise communications solutions including software, devices, and services.