Element for Android doesn’t support searching in encrypted channels and I think you can’t use E2EE in the browser at all(?), plus basically every other client has even more drawbacks when it comes to E2EE.
My team recently tried RocketChat, but E2EE is obviously an afterthought for that project as it has even more limitations than non-Element Matrix clients (no searching, no pinning, no file upload, no edit, etc.). Plus Jitsi integration seems to be buggy right now (at least on my Windows installation).
What else is out there that’s not on my radar? Is Matrix with Element really the best option right now? Is there no project that puts E2EE above all else?
Edit: Should be self-hostable and (FL)OSS.
E2EE works fine in browsers, but you run into the same challenges and worse when it comes to usability features like search. On desktop there’s (imperfect) indexing of encrypted messages so that you can search encrypted rooms, but I don’t think Android has that.
The server-side search feature, which most Android apps use, can’t search through your encrypted messages for obvious reasons. Element for Desktop and its forks maintain a local search cache, but this is quite CPU intensive to generate, especially if you’re signing into an existing account. I can see why they haven’t implemented this on mobile phones, you’d need to leave your phone hooked up to a charger overnight to generate such a cache without draining your battery.
I think this is the result of Element doing exactly what you suggest: support E2EE above all else, “all else” including “being able to search through chats”.
You may want to consider XMPP as an alternative to Matrix. I have no idea if and how E2EE search works on popular XMPP apps, but it’s worth a try.
I think the iOS client has that feature, but I unfortunately don’t have an iPhone to test that claim.
What clients/servers are recommended on each platform (for full encryption support)?
XMPP is old and has many clients. I think ejabberd is still the go-to server solution, but I haven’t kept up to date since switching to Matrix. Prosody also seems popular?
I’ve heard good things about Conversations as a client app for Android. I’ve seen Dino recommended a lot as a desktop application.
It’s hard to say what client serves your purpose best because there are hundreds of extensions to XMPP that have to do with all kinds of things, from “keeping the same history between devices” (which wasn’t in the original protocol!) to “use XMPP as a notification backend for third party apps” and “PubSub social media”. Check out https://xmpp.org/software/ for a list of the most common apps.
You’ll want to make sure to pick a client with modern (OMEMO) encryption support for the best interoperability with other people.