What are free or for adequate money modern engines of message boards?

Question

CMS

Advise if there are any free or inexpensive analogues https://tamaranga.com/products/doska/ ? And in general, what is the best way to make a bulletin board?
An important selection criterion is the ability to add nested categories with custom fields and search by them.

Answer 1

https://github.com/open-classifieds/openclassifieds2
https://osclass.org/