VIPole Secure Messenger!

With Viber, everyone in the world can connect. Freely. More than 460 million Viber users text, make HD-quality phone and video calls, and send photo and video messages worldwide over WiFi or 3G - for free. Viber Out can be used to make calls to non-Viber landlines and mobile numbers at low rates. Viber is available for many smartphones and platforms.

ChatSecure is a free and open source messaging app that features OTR encryption over XMPP. You can connect to your existing accounts on Facebook or Google, create new accounts on public XMPP servers(including via Tor), or even connect to your own server for extra security.

Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG].

Yahoo! Messenger is an instant messaging client developed by Yahoo! inc. for real-time communication of its users. It provides text chat, file transfer up to 2GB. conversations with audio and video, games. It also supports International Calling, Phone in Number and sending free SMS like Skype.

Open source Jabber (XMPP) client with multi-account support, clean and simple interface. Being both free (as in freedom!) and ad-free, Xabber is designed to be the best Jabber client for Android .

Chat everywhere! IM+ is the most widely used mobile IM app! Connect all-in-one to MSN, Yahoo!, Google Talk, AIM, Jabber, ICQ, Facebook, MySpace and Twitter on ALL popular mobile platforms.

KakaoTalk is a phone number based messenger service that allows users anywhere in the world to chat one-to-one or in a group for free. (no SMS service)

Encryption plugin for Pidgin, providing up to 4096 bit RSA encryption using the NSS crypto library from Mozilla. Keys are automatically transmitted and stored, making it very easy to use, but also resistant to man-in-the-middle attacks.