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.
- - Signal is the most popular Windows, Android, Mac & iPhone alternative to Sicher.
- - Signal is the most popular Open Source & free alternative to Sicher.
Telegram is a messaging app created by former VK creators with a focus on speed and security. It’s superfast, simple and free. It is like SMS, but more powerful.
- - Telegram is the most popular Web-based & Android Tablet alternative to Sicher.
WhatsApp is an iPhone and Android messaging app which allows you to exchange messages without having to pay for SMS.
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.
- - Zulip is the most popular Self-Hosted alternative to Sicher.
Threema is a 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.
- - Threema is the most popular commercial alternative to Sicher.
Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG].
Molly is an independent Signal fork for Android.
FluffyChat is an open, nonprofit and cute matrix messenger app for Ubuntu Touch, Android and iOS.
Status combines a private messenger, secure crypto wallet, and Ethereum Web3 DApp browser into one powerful communication tool. Chat with friends and growing communities. Buy, sell, store, and exchange digital assets.
An alternative Telegram client based on TDLib, with higher speed, slicker animations and experimental features.
Telegram X Features
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