TapTalk.io - TapTalk.io is a complete in-app chat SDK and messaging API - Easy integration and customizeable.
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Lets Chat - Open source self-hosted chat app for small teams
LightShot - The fastest way to take a customizable screenshot.
MongooseIM platform - The massively-scalable XMPPJabber mobile messaging platform, for mobile and web, by Erlang Solutions
Snagit - Screen Capture Software for Windows and Mac