QuickMSG is described as 'secure messaging format and an Android App of the same name. With it you can send messages either to other contacts directly or to groups. Its aim is to combine the ease of use that messaging apps give with the security of encrypted email' and is an app in the Social & Communications category. There are more than 50 alternatives to QuickMSG for a variety of platforms, including Android, iPhone, Android Tablet, Online / Web-based and iPad. The best alternative is Telegram, which is free. Other great apps like QuickMSG are Signal (Free, Open Source), WhatsApp (Free), Hangouts (Free) and Zulip (Free Personal, Open Source).
Signal is a messaging app with an unexpected focus on privacy, combined with all the features expected from a modern IM app. Signal has received a lot of praise from all around the world for its security and privacy-respecting technologies.
WhatsApp is an iPhone and Android messaging app which allows you to exchange messages without having to pay for SMS. In addition to basic messaging WhatsApp users can create groups, send each other unlimited images, video and audio media messages.
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.
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]. [Note] **You can download the compiled apk for free from F-Droid**: ...
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.