On iPhone, I recommend Monal.

Monal comes close.

To be honest, I think the above clients and services like Snikket fit that description.

Now, I wouldn’t say they’re all on the same level UX-wise as WhatsApp, Telegram etc. But I do think they are 90%-95% of the way there, and in my experience that’s enough to convince friends and family to switch over.

In my experience, when people haven’t wanted to switch, it’s normally not been because of the clients, but because they don’t want to install yet another app to talk to someone.

Any new open source software is always a net positive.

But, there are a few small caveats to the way they’ve done it (depending on how cynical/cautious you are):

• Because Proton are not accepting contributions, they own all the copyright, so can make the code closed source again if they want to (that wouldn’t affect the already released versions, but future versions)
• They could likely take down any derivative on iOS, since Apple will always take instruction from the copyright holder, for GPL’d code
• Since the builds are not reproducible, there’s no guarantee that the binaries they distribute are built from the source code

How do you define modern? I would call these modern clients personally:

• Android: Conversations
• iOS / MacOS: Monal
• Linux: Dino
• Windows: Gajim

Perfect, now you just have to wrap your program inside a debugger in production!

I’d like to second Snikket - it’s designed for this use case and is very simple to set up.

If you’d rather not use Snikket, check out these recommendations for clients and servers.

Hope it works for you! Feel free to reach out if you have any questions.

How I Got a Truly Anonymous XMPP Account:

• Open my client (e.g. Conversations, Monal, Dino)
• Pick a random server, username and password
• Click register

Sorry, it’s a cheap joke, but it still baffles me that Signal requires a phone number, so I felt I had to post it :)

Of course, this is not XMPP-specific either, just my protocol of choice, there are many other open alternatives that also offer such functionality.