FortKnoxster is described as 'multidevice easy-to-use private and secure messaging, calling, crypto wallet and cloud storage, using advanced end-to-end encryption and leveraging on blockchain technology' and is an app in the Security & Privacy category. There are more than 25 alternatives to FortKnoxster for a variety of platforms, including Android, Online / Web-based, iPhone, Windows and Mac. The best alternative is Telegram, which is free. Other great apps like FortKnoxster are Signal (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.
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.
Kosmi is a free real time application and communication platform that offers voice, text and video calls along with games and applications such as SNES Party, NES Party, OpenArena, Poker, Virtual Cardtables, Synced YouTube and Cowatch Video.
FluffyChat is an open, nonprofit and cute matrix messenger app for Ubuntu Touch, Android and iOS. Open Opensource and open development where everyone can join. Nonprofit FluffyChat is donation funded. Cute ? Cute design and many theme settings including a dark mode.