I'm surprised at the synfony and nodejs part too, but
@Nobita.Kun nodejs might have something to do with your messenger addon but I don't think it's a basic of xenforo.
@Robust I've had one from here and 3 from upwork that all had developed add-ons specifically for xenforo, as that's the only criteria I could use.. but all of them (from upwork) are here too.
As a matter of fact, the best - by far - I worked with didn't even know xenforo, sadly he took on a much bigger job than mine and didn't have more time, but that demonstrated that a great php developer even if he doesn't know xenforo can be much much much better than many I tried that are 100% xenforo skilled.
You didn't answer my question though
So, just php/mysql ? that's all ?
Mehdi