Redact is described as 'The world's first totally secure instant messenger application' and is an app in the Social & Communications category. There are more than 100 alternatives to Redact for a variety of platforms, including Android, iPhone, Windows, iPad and Online / Web-based. The best alternative is Telegram, which is free. Other great apps like Redact are Signal (Free, Open Source), Discord (Freemium), Jitsi (Free, Open Source) and Skype (Freemium).
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.
Whether you’re part of a school club, a gaming group, a worldwide art community, or just a handful of friends that want to spend time together, Discord makes it easy to talk every day and hang out more often. Create an invite-only place.
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.
Jami (formerly GNU Ring, SFLphone) positions itself as a potential free Skype replacement Open Source and cross-platform. Jami gives you a full control over your communications and an unmatched level of privacy.