Matrix like you. Most foss projects are in matrix as well. Matrix call is awesome.

There isn't a 1:1 app for Discord imo.
Selfhosting a teamspeak3 (ts3) server solves the voicechat.
Signal works great for text chats especially now that you don't need to give other end users your phone number.
Then I would probably look at hosting a web forum for adding calendars and other planning tools. There should still be possible to show current ts3 users on that site too.
For open source projects codeberg for code repository/issues/feedback.
I completely understand those who use Discord for ease of management, as time taken to host the above is time taken from the actual project.

If you still end up using Discord over other solutions, you can use https://vencord.dev/, it is discord, but with all the telemetry pulled out of it. Been using this for when I need to use Discord, assume it's better than using normal discord at least, but probably still not a perfect solution.

Mumble + IRC or XMPP works well.

If you just want group chat, Signal works well. It's more suitable for smaller groups though, so YMMV.

Other than that, Matrix works well.

Matrix is pretty good, only problem is my friend groups can't seem to make the switch. As in we all want to but we have other groups we talk to on discord so we'd have discord installed anyway, and I think some of us aren't motivated enough to move our server over. I think generally the problem with privacy-respecting chat apps is everyone's on whatsapp, everyone's on discord, few "normies" or even less privacy-conscious communists will want to install a new app/program just to talk to you.

Worth checking out for more privacy :

• https://briarproject.org

• https://simplex.chat

• https://molly.im/

Pretty much just matrix and revolt, armcord is a good client to use discord if you just need to use discord but eh

Spacebar is supposed to be a 1 to 1 discord alternative

FluffyChat?

Element, Matrix

How do we know that these solutions are more private than Discord?

Even if open source, how do we know the compiled version wasn't altered?

Element is not a solution, it is a client. Matrix is the protocol. Discord happens to provide both in a spectacularly privacy disrespecting way imo.

I know of two chat protocols which are quite popular: matrix and xmpp. Matrix seems to be the more flashy but also more energy consuming part. Xmpp is very old and apparently has been EEEd by google at some point which is the whole reason matrix exists imo.

As clients go, you can use one of dozens of them, each different. Element (and element x) are made by people who also are involved with matrix but run a for profit company as well so beware. They also make contributors sign away their rights if they ever wanted to take element closed source which is a red flag.

I mostly use fluffychat which isnt perfect but works very well imo. I also have bridges on my matrix server (i use synapse) which connect whatsapp, signal and discord for the folks who dont want to switch over but want to talk to me. This makes is convenient for me and I still have encryption and control over my data in the pure matrix chats.

I cant comment on running xmpp bc no experience but reports say its very fast. Running your own matrix server or using a known host means you have no ads, no tracking, e2ee and you will likely always know where your data goes.

Thanks for reading and have a good one.

I've used Revolt before. It's very similar to Discord superficially, but lacks a lot of features. Even though it's more similar to slack, I've found Mattermost to have more feature parity.

There is guilded.gg as well but I don't know if it's better for privacy.