Simphone is described as 'Secure and private open source peer-to-peer Instant Messenger' and is a instant messenger in the social & communications category. There are more than 50 alternatives to Simphone for a variety of platforms, including Linux, Windows, Mac, Android and iPhone apps. The best Simphone alternative is Signal, which is both free and Open Source. Other great apps like Simphone are Telegram, Element, Discord and Pidgin.
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.
United States
Secure communication for individuals, teams, and large organizations.
United States
Off-the-Record (OTR) Messaging allows you to have private conversations over any instant messaging (MSN,Gtalk, Facebook and so on) by providing encryption, authentication, deniability, perfect forward...
Bitmessage is a P2P communications protocol used to send encrypted messages to another person or to many subscribers. It is decentralized and trustless, meaning that you need-not inherently trust any entities like root certificate authorities.
qTox - The most feature-rich Tox client; P2P instant messaging, audio and video calls.
Estonia
EU
TeleGuard is the data-secure messenger from Swisscows. TeleGuard encrypts every message and all telephone calls with encryption algorithm currently available: SALSA 20. TeleGuard servers are located in Switzerland, they are not subject to the data protection laws of the EU /...
Switzerland
Quantum-resistant encrypted messaging, video/audio calls, and file transfers in the browser with optional registration and no downloads required.
United States
Open source Jabber (XMPP) client with multi-account support, clean and simple interface. Being both free (as in freedom!) and ad-free, Xabber is designed to be the best Jabber client for Android .
United States
Technitium Mesh is a secure, anonymous, peer-to-peer (p2p), open source instant messenger designed to provide end-to-end encryption. Primary aim of developing this instant messenger is to provide privacy which is achieved using cryptography and anonymity using Tor network.
India
µTox is the lightweight client with minimal dependencies; it not only looks pretty, it runs fast! µTox is available for Windows, OS X, and Linux (Android support is experimental), with full support for chat, file transfers, audio/video calling, and desktop sharing...
Canada
