Messenger!

WhatsApp Messenger is a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for iPhone, BlackBerry, Android, Windows Phone and Nokia and yes, those phones can all message each other! Because WhatsApp Messenger uses the same internet data plan that you use for email and web browsing, there is no cost to message and stay in touch with your friends.

Facebook Messenger is a faster way to message. Reach friends right on their phones, get and send messages fast, message everyone at once and more.

Google Duo is the cross-platform, one-to-one video calling app that's simple, reliable and fun.

SeaFour is the SeaFour.club community's chat engine, powered by Node.js and Socket.io.It's a socket webchat supporting aesthetic username customization and stylized messages using a markup language similar to 'LISP', and supports a multitude of alternative clients. It uses a free-as-in-freedom license that enables users to modify the software to best fit their needs.

mysms Messenger is a completely free messaging service that supports texting on your smartphone, computer and tablet. mysms works cross-platform and is always free of charge. Stay connected with your friends and family no matter where they are.

GO SMS PRO brings you cool UI, fast and convenient SMS/MMS experience. GO SMS Pro (yet FREE) is a huge enhancement for stock messaging app, much faster and more functions.

Open source instant messaging server and clients. Backend in pure Go (license GPL 3.0), client-side binding in Java for Android and Javascript (license Apache 2.0), persistent storage RethinkDB. JSON over websocket (long polling is also available). Tinode is meant as a replacement for XMPP. Overall it's a lot like open source WhatsApp or Telegram.

VideoMeeting is a free and open source video conference solution built to have video calls and chats using your web browser. It is deployed on top of hubl.in. It is a pure web application based on WebRTC that can provide communication features within your web browser without needing to install anything.

Ever received an SMS from a stranger? Hate receiving spam SMS?Truemessenger by Truecaller tells you who sent you that SMS (even if they are not in your contacts) and automatically blocks spam, keeping your Inbox safe and clean.