WhatsApp WhatsApp is a cross-platform mobile and web messaging app that was developed by American company WhatsApp Inc., based in Mountain View, California. It uses the Internet to send text messages, images, video, and audio media messages. WhatsApp is freeware without any monthly fee.
Wickr Wickr is an end-to-end encrypted mobile application for encrypted texting and file sharing. Wickr is available for both iOS and Android and is free to download.
ChatOn ChatOn is a cross-platform mobile application that supports a variety of mobile devices. It was developed by Samsung Electronics and is available on Android, BlackBerry, and iPhone.
Skype Skype is a P2P application that allows users to make voice and video calls to other Skype users for free. Skype is available for Windows, Android, iOS, Mac OS, and Linux.
Slack Slack was founded in 2009. Like DingTalk, it is a messaging app for team communication. It offers both a free version and a paid version.