Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Q&A for work
Connect and share knowledge within a single location that is structured and easy to search.
This is an example of the forum software: https://community.aseprite.org/
I have seen many communities with identical design, suggesting that they use the same self-hosted software.
Is that an open-source software and, if so, which is it?
That is the Discourse forum software.