Zulip has many of these features I believe. Anecdotally it seems to be great for running an online discussion forum for a high school or college level class.
I only sent like 3 messages, but it was awfully slow. Didn't come away with a good impression.
I ask because we have a known issue in Zulip that the first minute or two of using the product is quite slow for folks with 100K for unread messages because it the web app's client-side data fetching system ends up fetching them all in order to make clicking around the app afterwards extremely snappy.
We've reworked that system over the last few months, and it'll be deployed to Zulip Cloud next week if all goes well. But if you don't have a lot of unread messages, I'd very much like to understand why -- I'd love for you to stop by chat.zulip.org and debug with us a bit if you can spare a bit of time.
(It could be that the Lean community Zulip involves rendering a LOT of LaTeX, for example)
You are right. Lean community had about 3K unread messages for me. After I marked a whole bunch read, and clicked around a bit, speed is now good.
Thanks for making me check.
My only other feedback would be that there is a new user "tutorial" or rather the interface highlights certain aspects of the UI for the new user. The bubbles that pop up for this, are too small and not noticeable on a dark theme. Make them bigger and different color.
Just to clarify for anyone here reading, Zulip can be scaled out, but largely our philosophy is that you should only scale out if you need to, since it comes with extra fiddly operational headaches and is expensive in dollars. We've designed Zulip with an efficient data model and well-indexes queries, and are constantly working as we add new features to maintain the property that only multi-tenant installations like Zulip Cloud should need to scale it out.
In particular, Zulip on a single server with 16GB of RAM can handle 10,000s of users, thousands of which are concurrently active. (That's what we use for chat.zulip.org, for example, and the machine is usually about 96% idle with only half its memory used).
(Keep in mind that Zulip's public access option means you don't need every user to create an account in order to access content).
I don't know your context, so I can't comment on whether zulip would be suitable. But there are very few communities today having complex conversations involving 100K+ people in a single organization/workspace, so I would expect it to be quite rare that autoscaling would be relevant. (Certainly there are Discords with over a million users, like the Midjourney one, but most of those users are just users the product, not having discussions at all; the company famously made the unusual decision to only offer a Discord bot as UI for their product).
https://zulip.readthedocs.io/en/latest/production/requiremen... has some basic guidelines on Zulip's scalability for a single-instance deployment, but those are fairly conservative -- the goal is for folks to be able to deploy with those settings and be safe even if their load profile per user is fairly heavy for whatever reason.