[freeqaz]

This is still a hard problem today. Some hard tech was built for this. I'm excited for a world where this is more accessible and less hardcore than something like CRDTs (in terms of accessibility).

How have others noticed the world shifting in the past 6 years?

[danielvaughn]

There are now a few sync engines that tackle this problem. Rocicorp Zero, Electric SQL, and one or two others. By no means a crowded space, but there are options now.

edit: links

  https://zero.rocicorp.dev/
  https://electric-sql.com/

[reb]

Have you had a chance to use either of these yet? Electric looks like an obvious mature choice — curious if you think Zero's approach is compelling enough to be worth trying in alpha

[danielvaughn]

Haven't used either of them. I met the guy behind Zero and he's super smart. He had been working on Replicache for a long time before he started this thing.

That being said, I haven't tried them, so can't really give an educated opinion. But I feel pretty confident in the domain expertise on the Zero team.

[andrewmcwatters]

All the fundamentals have existed for at least 26 years. So, no, not really.

It's also really weird to use video game terminology and ignore the fact that all of the approaches used in this article have in fact, been done by major game engines, are readily documented in game development circles, etc.

It reads like an undergrad discovering game development for the first time. None of this is novel. It wasn't even novel for a web or desktop application to use.

[Rohansi]

I also found it weird. They're basically doing what multiplayer games do but for a web app. Not the typical way you'd build your web backend but nothing actually new... not even using CRDTs, just inspired by them.

[andrewmcwatters]

Yeah, if anything it’s obvious how you’d implement multiplayer for web apps.

By using multiplayer architecture…

And all their talk about state reconciliation? That’s just server authority…

[partdavid]

Can you say more about which prior art you think overlaps here? We have a similar use case to Figma and are implementing a similar solution. I'm not particularly concerned whether the path we're following is novel but I am particularly concerned with whether there are gotchas along it that we should be watching out for, so if there are more mature solutions, we'd be interested.

[andrewmcwatters]

Read QuakeWorld 1999, client-server prediction, Counter-Strike: Source lag compensation.

See also, “reconciliation.”

Also, debatably the article hints towards an incorrect implementation because they specifically mention sending events instead of user input.

By design, if you do this, you can create events that are supposed to eventually stop, but the user may drop packets and disconnect all the while you were processing an event that was never supposed to occur.

If you poll user input and experience loss, there’s no event to misfire.

This behavior manifests itself in games as a player that continues to walk forward despite having lost their connection to a server and is a indicator that a multiplayer server was implemented incorrectly.

[Rohansi]

Multiplayer video games are the big one. There's no reason why you couldn't apply the same kind of synchronization to a web app. You'll just need to decide on an approach because not all games do it the same way. Most likely you'd want rollback netcode.

[mweidner]

Indeed, Replicache works this way, using server reconciliation (one part of client-side prediction): https://doc.replicache.dev/concepts/how-it-works

[asnyder]

I know Liveblocks.io has been making this very easy and accessible over the last few years. They recently introduced AI, and are promoting that of course, but as I understand it multiplayer collaboration (https://liveblocks.io/multiplayer-editing) is their meat and potatoes.

Not affiliated with Liveblocks, just aware of its existence.

[ctnicholas]

I work at Liveblocks—yes! Our founders were inspired by Figma and wanted to make it possible for others to build apps like this more easily. We provide our own sync engine, Storage, which is aimed at this use case.

[winrid]

Sharedb/racer solved this like 10yrs ago. You get synchronized snapshots, conflict resolition, diffs, change tracking..

[simultsop]

There were some additional posts regarding the topic by same guy. https://hachyderm.io/@evanw

Innovators like him, are very rare.

[wrren]

Elixir's Phoenix LiveView + PubSub covers a lot of these bases out of the box.

[thruflo]

PubSub and LiveView do go a long way. However, broadcast isn't sync and LiveView isn't appropriate for all applications.

Phoenix recently added Phoenix.Sync [0], a sync engine library explicitly designed [1] to address this. In combination with a front-end library like TanStack DB [2] it goes much further towards giving you a Figma/Linear-style sync engine out of the box [3].

[0] https://hexdocs.pm/phoenix_sync [1] https://www.youtube.com/watch?v=4IWShnVuRCg [2] https://electric-sql.com/blog/2025/07/29/local-first-sync-wi... [3] https://electric-sql.com/demos/burn

Disclaimer: Electric founder. Linking to my own talk / post / demo.

[willmartian]

A sync engine plus the always online nature of LiveView feels at odds with offline-first (which is often associated with sync engines). I wish LiveView had a better offline story.