Forum Software Similar to Reddit?

This is not an exact answer to your question and I have not tried this one, but Postmill [1] is similar to HN and phpBB [2a] is an off the shelf forum platform with incredible moderator capabilities but I think an add-on/extension [2b] is required for voting. the linked addon is closer to github style reaction voting

Some have suggested that Lemmy [3a][3b][3c] is an alternative to Reddit but I have never tried it. An alternative to Lemmy appears to be Kbin [4a][4b]. I've never run either of those.

[Edit] Found another called Strimoid [5a][5b] Excluding all the other ones I found as they require javascript to browse anonymously like Mastodon.

[1] - https://gitlab.com/postmill/Postmill

[2a] - https://www.phpbb.com/

[2b] - https://www.phpbb.com/community/viewtopic.php?f=456&t=239726...

[3a] - https://join-lemmy.org/

[3b] - https://github.com/LemmyNet/lemmy

[3c] - https://news.ycombinator.com/item?id=36376373

[4a] - https://kbin.social/

[4b] - https://codeberg.org/Kbin/

[5a] - https://strm.pl/

[5b] - https://github.com/Strimoid/Strimoid

Lemmy and kbin are the most similar to Reddit I have seen so far.

kbin appears to be very young and beta-grade at best, though under active development.

Here's a couple of links for you to investigate... https://news.ycombinator.com/item?id=32368029 https://github.com/GorvGoyl/Clone-Wars

Lobste.rs is open source (https://lobste.rs/about), and they say that the software is being used to run some sister sites (list here: https://github.com/lobsters/lobsters/wiki). I'm not sure how easy it is to just grab and run, though.