Ask HN: Developer to pitch idea for side project?

Hello HN.

Where are the best places to pitch developers, so that they may take on a side project in their spare time?

I'm looking for an experienced backend webrtc developer, that knows Golang and is well versed in Video and Telecom.

It's probably a few months work and I want to negotiate on payment as well. (to make things a bit more complicated)

Does anyone know of any sites where developers are looking for a challenge?

Rather not use upwork, freelancer.com, etc.

Thanks!