I suspect that jobs being posted to smaller niche job boards (such as Authentic Jobs, which I hadn't heard of until this post) is down overall, but this doesn't reflect the state of job availability.
I believe larger job sites are having enough of a network effect that these boards are becoming less relevant. Most tech job seekers I talk to are going one of four routes.
1) LinkedIn (Facebook for job seekers)
2) Indeed (since it aggregates)
3) Direct application (when you know a specific company you want to work for)
4) Recruiters (Let them do the work for you...)
On the anecdotal front (within the past year) I have been contacted twice by recruiters that took me out and bought me lunch to try and woo me to another job and once contacted directly by the CEO of a company who did the same thing. I want to make this point clear; I'm no one special just a regular software dev with 15+ years working experience.
During one of these lunches the recruiter said to me, "It is so difficult to hire qualified developers that I would say there is a NEGATIVE unemployment rate currently."
I have spoke with multiple company owners, CEOs, and others who are in the hiring position and the general consensus is they can't find qualified help.
This is just my experience.