- Discourse (modern and popular) — Ruby
- Talkyard (inspired by Discourse and StackOverflow) — NodeJS
- Forem (Unique approach for a community platform)
- NodeBB (Modern and full of features)
- Vanilla Forums (enterprise focused)
- bbPress (from WordPress)
- phpBB (classic forum software)
- Simple Machines Forum (another classic)
- FluxBB (old school)
- MyBB (less popular but worth a look)
- Flarum
- Bonus: Lemmy (More like a Reddit alternative but a decent option)