Ask HN: What is the best channel to reach developers, as a audience?

Guys, we are building an online service for coders to prove their coding skills, share knowledge with other developers and learn new coding skills/methodologies and it's called Skilleo (http://skilleo.me).

Now, our biggest challenge, like the rest of SaaS or mobile apps is getting user growth/traction.

Right now we are focused on the user acquisition.

So, in your opinion as a techy guy/developer/coding aficionado, what do you believe is the best channel to reach you and how the approach should be made? (no, not the 90's way of the "Try Now!" approach...)

Thanks and cheers Joao