Kiax!

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.

Mumble was the first and is the most successful and wide spread free and open source software for VoIP. It was the first VoIP software to provide low-latency audio suitable for gaming, and at the same time was a pioneer in high audio quality at the same time.

See up to 8 friends on live video while chatting with them! Create your own room (appear.in/your-room) and send the link on chat, Facebook Messenger, SMS or email to invite people. No registration required, once people click the link, they'll appear with you!

Zulip is a group chat app.

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

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.

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.

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.

Photo4tune is a free application that provides a simple way to capture and share the best moments of your life on your Android phone. All the photos you post will appear on the world’s map showing the place they were taken. Photo4tune also introduces a new way of communication, allowing you to set a visibility timer for your messages.Joining Photo4tune is easy: your phone number serves as your ID. The app syncs with your mobile contact list and automatically detects which of your contacts have a Photo4tune account. Features:• Chat and share photos with other Photo4tune users• Send fire-messages to others, which will disappear from conversation page (though the messages will be deleted from servers after being viewed, recipients can save them by taking a screenshot)• Capture and share photos with the option to post them anonymously• Interact with friends through giving and receiving likes and comments• Share photos to other social networks like Facebook, Twitter, Flickr, Google+, etc.• Create private or public events and invite your friends to them• Due to push notifications you will never miss a message or comment, even when Photo4tune is turned off• Search by different criteria: by location (photo capture location appears on the map via GPS coordinates) »

VoipBuster is a free program that uses the latest technology to bring free and high-quality voice communications to people all over the world. When you use the free VoipBuster software, you can call regular phones in various popular destinations for free or call at an incredible low rate to any other phone on the planet.