Glassdoor.com is a pretty good guide for tech salaries. The salaries are self-reported, but they are aggregated and anonymous, so there is little incentive for people to exaggerate.
How would fluffing the salaries benefit a company? The result would be new employees expecting matching wages and existing employees feeling they are underpaid relative to their peers.
It certainly would benefit recruiting agencies; 20% of a bigger $ goes right to their bottom line. Not that they do that, of course, but I'd be slightly skeptical of any #s that come out of recruiting agencies.
In this case, any fluffing recruiting agencies do actually works in favour of good software developers.
You could make a claim that if the salaries weren't pumped by the recruiters, the employers could hire more people, but by all accounts lack of jobs isn't currently a problem for good developers.
HR makes the sell that "after a few years the candidate -could- be making that kind of money". The few years never really come, so the employee moves on. Except that the next company makes the same commitment.
By that metric just about every millionaire, and most every founder or cofounder billionaire, is an idiot. (Or was when they invested the time and energy to be where they are today.)
