How Figma’s multiplayer technology works (2019) | Hacker News Reader

How Figma’s multiplayer technology works (2019)

figma.com

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Linear's write ups / talks on real-time sync are also very good, if a bit old now.

1. https://www.youtube.com/watch?v=WxK11RsLqp4&t=2169s

2. https://linear.app/now/scaling-the-linear-sync-engine

Also see this overview of related tech here:

3. https://gist.github.com/pesterhazy/3e039677f2e314cb77ffe3497...

And c.f. automerge from ink & switch:

4.https://automerge.org/blog/

Just to say if you're interested in this kind of tech and are in the Bay Area, Sync Conf [0] just announced [1] its initial speaker lineup today and Arushi Bandi from Figma is one of the speakers.

[0]: https://syncconf.dev [1]: https://x.com/sync_conf/status/1957818840777122293

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?

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

Innovators like him, are very rare.

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.

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.

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

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.

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.

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/

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

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.

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.

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.

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.

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

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