Threema is described as 'New mobile messaging app that puts security first. With true end-to-end encryption, you can rest assured that only you and the intended recipient can read your messages' and is a very popular instant messenger in the security & privacy category. There are more than 100 alternatives to Threema for a variety of platforms, including Android, iPhone, Windows, Mac and Linux apps. The best Threema alternative is Signal, which is both free and Open Source. Other great apps like Threema are Telegram, Element, Tox and WhatsApp.
Smoke Messenger is an open-source Instant Messenger that is known as the first mobile Messenger worlwide using the encryption algorithm McEliece. To be downloaded at F-Droid.org or Github.com. Smoke provides with its own Server-Software: SmokeStack-Echo-Server.
Anonymous and fully encrypted peer-to-peer instant messenger for Android using onion routing (via Tor)!
Reclaim your privacy With Uup. Just download the app and start chatting. Uup App is based on asymmetric encryption. Private key is generated based on the device and it doesn't need any email, mobile number or anything else to work.
The one and only secure messaging app Protect your privacy!
SECURE MULTIMEDIA MESSAGING
Converse is a messaging app for decentralized, secure, end-to-end encrypted conversations. Built on the XMTP network, Converse lets you own your conversations and take them anywhere whenever you want, ensuring your most important messages—the ones you never want to lose or be...
WireMin is a decentralized network built by the people, for the people, and of the people. Enjoy full privacy and security with end-to-end encryption on a network without central servers. Your data stays under your control—free from censorship, surveillance, and exploitation.
Confide lets you take your messages off the record:
Graph Messenger is an UNOFFICIAL messaging app that uses Telegram's API and add new features like real multi account system, download manager and time line.
Messenger for WhatsApp™ (WA Messenger) is a wrapper for WhatsApp Web. It loads WhatsApp Web in toolbar popup UI and has badge icon text notification for all new conversations (even if toolbar popup is closed).
White Noise aims to be the most secure private chat app on Nostr, with a focus on privacy and security. Under the hood, it uses the Messaging Layer Security (MLS) protocol to manage group communications in a highly secure way.
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