Snapchat - Real-time picture chatting

Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.

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.

tcpdump - tcpdump is a common packet analyzer that runs under the command line.

StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS

netcat - Netcat is a featured networking utility which reads and writes data across network connections...