It'll take some setting up, but matrix may suit your needs: https://matrix.org/bridges/

I agree with you. However it won't solve the problem of privacy regarding Facebook. Other issue that I see here, people want an unified messenger, with a great user experience, 100% secure, open-source, multi-platform, free (as in beer) and no monetization included. I'm sometimes shocked that here - hacker news - people underestimate the price of good software development, infrastructure and maintenance.

Even a tiny amount of monetization should pay for development of a chat app...

Imagine you build it with a team of 5 software devs for each of linux, mac, windows, android, ios, web. You build it in Europe paying a generous salary of $80k. You need 1 server per million users (as whatsapp did pre-acquisition), hosted on say AWS. If you get 10% of the world to use it, the total running costs are 1.2 cents per user per year.

That can totally be paid for by sending each user 1 sponsored chat message per decade. That's a pretty acceptable level of advertising I'd say.

It's incompatible with VC's demanding hockey-stick revenue growth though...

> Imagine you build it with a team of 5 software devs for each of linux, mac, windows, android, ios, web. You build it in Europe paying a generous salary of $80k.

Optimistic and dangerous. You will need at least a visionary person like Moxy willing to dedicate his/her life to the project. You need a master mind to get all the security architecture right. BTW You will need an operation team and multiple servers to make sure that everything runs stable. Just look the costs for running COVID-19 apps. Development and operation. Million of Euros. You can expect similar costs to run a service able to compete with WhatsApp.

You forgot about the support staff. For example, Telegram blocks from a few hundred to a few thousand terrorist propaganda channels each day. I think that's just the tip of the iceberg.

Man, I’m getting old. Back in the day, we had Trillian and Pidgin for that, among others.

I think the newer services are less interested in integrating or have weird and unique features that are harder to implement.

I agree though, it would be nice to be able to have Matrix, Discord, Telegram, Signal all on one program and with all their established features.

There used to be on Android, it's called Disa, but a lot of services actively combat third party clients.

It was nice when I used it back in like 2014 because if WhatsApp went down I could just keep talking to the same person via Telegram (assuming they had both) and it'd all be in 1 joined conversation.

I remember using Disa as well. It's a long time since then.

Is there a reason why there isn't a client that can work with matrix/signal/telegram/any service with open source clients available? Are there any existing OSS projects which have made any progress in this domain?

People are right, it doesn't solve the issue with Whatsapp, but it would mitigate some of the barrier caused by the network effect. I'm also sceptical of walled gardens, something usable in this domain would make this less of a problem when some drama rises over Telesignix, switching clients is a lot less of an ask than switching everything.

Platform providers like Google and Apple could tear down app walled gardens by simply saying "If your app has a significant chat component, it must make available this API to allow other apps to integrate with it".

Suddenly multi-billion dollar chat apps with big network effects are mere service providers... And since Google has failed so many times at producing a popular chat app, I'm surprised they haven't gone down this route...

They wont allow it. Then they would have to pay the cost for server infra while not being able to push ads via the client. The problem is how to get money to pay employees and make profit. If you want an open messeging app/protocol it would have to be mostly peer to peer to save on server cost, and developed by voulantenteers, and servers hosted by the community.

Trillian?