Mobile-Friendly Open-Source, (free?) Bulletin Board Recommendation?

Brethren:

Can anyone recommend a decent open-source bulletin board application?

I've looked at

- PHPbb: My 1st choice right now
- MyBB: Lacking in mobile-friendliness

Of course I'd prefer free but would be willing to pay a reasonable amount for a crackerjack forum.

Any recommendations are sincerely appreciated.

Thanks,
Keith

 

https://xenforo.com/ Is what elitetrader uses.

 

https://xenforo.com/features/app/ Has an app

 

Discourse is pretty popular, At https://www.discourse.org/ and https://github.com/discourse/discourse
It's web based, so no separate mobile apps, but works well on mobile for me.