Snapchat - Real-time picture chatting
Social Templates Bundle for Instagram - Large bundle of 240 posts & stories templates for Instagram
Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.
SocialSizes - Sketch templates for sharing images & videos on social media
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Video Templates By VEED.IO - Professional & editable online video templates for social