After WhatsApp updated its privacy terms and millions of users got angry, people started to move from it to Signal and Telegram. It even caused some problems for Telegram and Signal servers as they didn’t expect that much users.
Signal is known for its encryption and privacy and I think they are doing a very good job but I don’t trust them. The thing against Signal is that it’s not really free software. Signal has a code/repository that is published with a free (as in freedom) license but the app itself is not libre.
Signal’s app is not on F-Droid. The only way to get Signal’s app is to download it using Google Play Store. When many people complained, they published an APK which is really really hard to find and is still using Google Play Service, if it’s available on your phone.
Signal doesn’t let you connect to Signal using the app you created yourself. Even if you compile their exact source code, it will only be active at most for 90 days.
But what I use instead of Signal and Telegram? I use Matrix and XMPP. They are decentralized messengers and truly free (as in freedom). With Matrix and XMPP, I have true liberty over my computing and messaging. I can run my own server if I don’t trust others and I can make sure encryption works the way I want.
I can compile/build my own app and know for sure that the app works as it is expected. Unlike WhatsApp, Telegram, and Signal which have centralized servers, Matrix and XMPP are decentralized and there’s no main server. I know for sure what’s happening on the server (as I can run my own) and I’m sure the app communicates with server exactly how it says so or I want it.