I haven't used it from the hiring side, but I've seen a decent number of early stage companies using cord.co. There's also a startup called Otta - https://otta.com/. Not affiliated with either. Edit - AngelList also has job postings.

From the being-hired side, I was hired by Chess.com when the CEO found my chess app on GitHub. I think that was one of his main hiring strategies - look for chess-related projects and get in touch with the authors.