Tango is described as 'allows you to easily connect with friends & family or make new friends. Make video & voice calls, send text messages, play games, send music messages powered by Spotify and more all for free' and is an app in the Social & Communications category. There are more than 100 alternatives to Tango for a variety of platforms, including Android, iPhone, Windows, Online / Web-based and iPad. The best alternative is Signal, which is both free and Open Source. Other great apps like Tango are Jitsi (Free, Open Source), Skype (Freemium), Wire (Free Personal, Open Source) and WhatsApp (Free).
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.
Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, GTalk/Hangouts extensions, as well as OTR, ZRTP, etc.
Skype is the most popular free voice-over IP and instant messaging service globally. It allows users to text, video and voice call over the internet. Users can also call landlines and mobiles at competitive rates using Skype credit, premium accounts and subscriptions.
Wire is the most secure collaboration platform featuring messenger, voice, video, conference calls, file-sharing, and external collaboration –all protected by the most secure end-to-end-encryption. Why Wire?
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.