Element is a secure collaboration and messaging app based on the Matrix protocol. It’s decentralised to deliver digital sovereignty, and based on an open standard for easy connections and interoperability. It is end-to-end encrypted by default.
- - Element is the most popular Web-based, Windows, Android & Mac alternative to Talkonaut.
- - Element is the most popular Open Source & free alternative to Talkonaut.
With the rise of widespread government monitoring programs, Tox is an easy to use application that allows you to connect with friends and loved ones without anyone else listening in.
WhatsApp is an iPhone and Android messaging app which allows you to exchange messages without having to pay for SMS.
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.
- - Wire is the most popular SaaS alternative to Talkonaut.
Zulip is the only modern team chat app that is designed for both live and asynchronous conversations. Zulip topics create a separate space for each discussion, so different conversations will never get in each other's way.
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.
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.
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 .
The project seems no longer developed since 2019. Last version, 2.6.6, released in October 2019, can be still downloaded from F-Droid, it's no longer available on Google Play Store
Video conversations with up to 8 people in your browser - no downloads, no login. Just name your channel and you are on. Works in all modern browsers, even mobile.
Chat everywhere! IM+ is the most widely used mobile IM app! Connect all-in-one to MSN, Yahoo!, Google Talk, AIM, Jabber, ICQ, Facebook, MySpace and Twitter on ALL popular mobile platforms.
The widest selection of unique features that you won't find in any other IM client!.
WeeChat is a free chat client, fast and light, designed for many operating systems. It is highly customizable and extensible with scripts.
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.