Talk2Me!

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.

Zulip is a group chat app.

Zello (formerly loudtalks) the fastest way to communicate online. Don't type or call — just push F7 and speak! Reply, when convenient, talk to all people in a group at once or anyone individually, re-play the entire conversation later from voice history. It works on Blackberry, iPhone, Android and Windows Mobile devices too.

Dasher lets you do more than just text message. It's messaging with benefits:

Turn your phone into a Walkie Talkie.

Sesame is a messaging app that gives you a self-aware digital assistant to protect messages on your behalf: your own Personal Cognitive Messenger™.

WowApp helps you do good through the Power of Sharing. We share all revenues with you. WowApp Messenger is free and you can receive earnings without ever spending money.

Tribe is the easiest way to message. Just press and hold to record a message. Release to send.

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.

Chat with people you know, or find new friends.Main Features:Share messages, photos, videos, sound/voice recordings and location.Notification of messages when application is not running.Profile picture and about information.Create your own groups or join existing ones. Groups can be public or private.PIN code to lock application and protect your privacy.Set favorite contacts and groups.Manual and automatic deletion of messages.

Turn your smart phone into the ultimate push to talk walkie-talkie with TiKL.

VoicePing is a Smartphone based app that gives you the function of PTT and more!All packaged with an intuitive app, secured environment and simpler deployment, it's way better than PTT. It offers Lower Cost on Device and Plans, Unlimited Use at One price and an Infinite Range & Indoor Coverage.