been using this for years.. it doesn't have the GCM crap and hence works on de-googlified custom ROMs as well. Surprised how many people don't seem to know about it.
There are a few reasons for that.
1. The link to APK cannot be found on the official site[0], so it needs to be looked up in a search engine.
2. Even when downloading from the site, they try to scare you away with a warning [1]. The reason for warning could be avoided by hosting their own F-droid repo, but they refused it, claiming you can download APK and not listening to reason[2].
Though for people using F-droid can still get Signal through the Guardian repository [3]
Thing about the signal APK and the Guardian one is that, it still have the so called "crap" in the final APK, it just runs a background service when required google services are not detected, causing battery drain for many[4].
The drain could also be avoided by supporting UnifiedPush (it can fall back to FCM when it's detected), but they don't want to do that either[5].
[0] https://signal.org/download/
[1] https://signal.org/android/apk/
[2] https://community.signalusers.org/t/how-to-get-signal-apks-o...
[3] https://guardianproject.info/fdroid/
[4] https://github.com/signalapp/Signal-Android/issues/9729
[5] https://community.signalusers.org/t/use-gcm-fcm-alternatives...
> Surprised how many people don't seem to know about it.