Correction: Zulip is not centralized [LWN.net]

Correction: Zulip is not centralized

Posted Feb 22, 2026 15:39 UTC (Sun) by tabbott (subscriber, #60572)
Parent article: Open-source Discord alternatives

> Since Zulip is centralized, users on one server cannot easily and directly talk to users on another server.

Just a correction on the terminology: I lead the Zulip project and was quite surprised to see Zulip described as "centralized".

It seems the article mixes up "centralized" with "federated", which are independent concepts. Zulip is not centralized: Self-hosted Zulip servers can be completely self-contained, with the typical server only making outgoing network requests when it is configured to do so and to support a feature that is impossible without those requests (sending email, sending mobile notifications, fetching websites for previews, etc.).

Zulip clients are designed to support connecting to many different Zulip servers. So with Zulip, you can absolutely chat with people who primarily use a different Zulip server with your Zulip client without installing anything new -- you just need to do the bit of overhead of making an account on that other server. There's a valid debate to have on what the right security/account management model is -- there are benefits to having a "single" account that federates to other servers, and benefits to the accounts being independent, which makes moderation and data portability a lot simpler. (There's also several FOSS clients, like Rambox, Ferdium, and Pidgin, that support lots of chat protocols in a single app, so you don't need server-to-server federation in order to have the human user experience of chatting with whoever you like from a single app).

But that's about federation, which is just a different axis from centralization. You can have centralized but federated (say, the US banking system, or email, where not using a centralized service for spam filtering is impractical) or decentralized but not federated, like Zulip.

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Correction: Zulip is not centralized

Posted Feb 22, 2026 17:16 UTC (Sun) by iabervon (subscriber, #722) [Link] (2 responses)

I think the right way to phrase it is that Zulip is not centralized but that a Zulip server is centralized. Any particular conversation happens in a single place, with exclusively participants known to that place; conversations that happen in a different place have participants whose identities are not connected to the identities in the first place, even if the same client has both of them. On the other hand, the same server and client software and protocol can be replicated many times; while Facebook and Discord are different software with a single instance of each, different Zulip installations work the same way and run on the same software.

Correction: Zulip is not centralized

Posted Feb 22, 2026 18:10 UTC (Sun) by josh (subscriber, #17465) [Link] (1 responses)

I think "decentralized but not federated" captures that nicely.

I'd say that's probably the biggest difference people would end up dealing with, if they switch from Discord to Zulip: you have one account per server, and DMs are per-server.

Correction: Zulip is not centralized

Posted Feb 23, 2026 2:04 UTC (Mon) by iabervon (subscriber, #722) [Link]

I think of "decentralized but not federated" as like classic IRC, where there were multiple disconnected networks (so, not federated), but each network also had no single server necessary for having a conversation on that network (users would pick somewhat randomly between servers that weren't too far from them).

None of these options are going to be centralized in the sense of having only one instance, since anyone can get the server software to run their own instance.

Correction: Zulip is not centralized

Posted Feb 23, 2026 14:05 UTC (Mon) by daroc (editor, #160859) [Link] (3 responses)

That's an interesting distinction. It doesn't match my understanding of the definitions of 'centralized' and 'federated', but I can see how your version holds together. I tried to get around terminology issues by putting in that little definitions box, but clearly that was insufficient. My copy of Merriam-Webster does not have the technological definitions, unfortunately, just the historical ones.

Correction: Zulip is not centralized

Posted Mar 9, 2026 1:14 UTC (Mon) by tabbott (subscriber, #60572) [Link] (2 responses)

In my view, Signal or Proton would be good examples of apps that are open-source but centralized and not federated. (Well, email is federated, but I think Proton has various services that are not).

If you can self-host a self-contained server, and thousands of people including the majority of actual users in fact do that, I don't think there's a serious sense in which it is centralized.

Correction: Zulip is not centralized

Posted Mar 9, 2026 7:05 UTC (Mon) by zdzichu (subscriber, #17118) [Link] (1 responses)

FTR, Signal was federated some time ago. There was another client WhisperPush shipped with CyanogenMod for Android devices. Federation ended and was deemed "degrading user experience" and "holding back development".

Correction: Zulip is not centralized

Posted Mar 9, 2026 10:28 UTC (Mon) by paulj (subscriber, #341) [Link]

Or holding back Five Eyes¹ monitoring

1. They prefer to call themselves the "Five Sisters", amusing institutional sensitivity.