Any open source stack exchange clone

The software is QPixel. It was built specifically to be an open-source discussion system a la Stack Exchange.

The largest public instance of it that I know of is codidact.com; codidact.org is the sponsoring organization.

https://github.com/codidact/qpixel

In the bioinformatics sphere there is this MIT-licensed Stack Exchange clone: https://github.com/ialbert/biostar-central

Discourse might be an option

https://www.discourse.org/

Codidact is a literal direct competitor to StackExchange, and it's open-source: https://codidact.org/

I explored this a bit and found there is a threshold of "too many tools" where people won't follow things on yet another thing that sends them notifications.

I think the magic number is 4: email, chat, wiki, tickets - we don't do much email so more like 3. The problem is none of those are good at longer technical discussions. With chat, threads beyond a day or so in the past are clunky to revive and follow. Wiki is better at finalized docs, tickets are short lived and any technical discussion should be settled by the time someone is working an item.

Really curious if others have found solutions.

Are you looking for something hosted by another organization? I'd say just use the old version of Reddit from when it was still open source as long as you're willing to self-host (https://github.com/reddit-archive/reddit/wiki/Install-guide). I believe that is what Less Wrong originally did. The features that Reddit has added since don't seem useful to me anyway.

For a Stack Exchange-alike, the ROS project hosts one at https://answers.ros.org which is powered by Askbot (https://askbot.com/), which says it is an open source Django app, but I didn’t see the code at a quick glance.

The Lobsters codebase is available, it's a straightforward Rails app with few dependencies: https://github.com/lobsters/lobsters

I used this about a decade ago. No complaints. https://github.com/q2a/question2answer

There is TalkYard: https://www.talkyard.io/

A forum, stack exchange is an instance of the forum pattern of communication.

https://www.codidact.org/

https://github.com/LemmyNet/lemmy

"... Lemmy is similar to sites like Reddit, Lobste.rs, or Hacker News: you subscribe to forums you're interested in, post links and discussions, then vote, and comment on them. Behind the scenes, it is very different; anyone can easily run a server, and all these servers are federated (think email), and connected to the same universe, called the Fediverse."

We're currently in the process of leveraging Github discussions for that.

Which are the features you need the most?

Discourse

Stack Overflow for Teams

Google nntp

Q2A

Scoold