There are a few -- Glassdoor, and Google reviews let you post bad reviews of businesses even if they have tons of money. That's not to say I disagree that big money runs things, just that it's not 100%.
Glassdoor is gamed. I've spoken to some multiple HR people who make fake reviews for their employer to counteract some bad reviews. I wouldn't trust it for smaller companies.
I've been asked by a shitty (billion $ plus) company to write one of these type of unjustified positive reviews, directly after the rest of my devops team had quit and only days before I handed in my own notice. Needless to say I declined.
There were stories here on HN (might dig them up) about how Glassdoor blackmails companies with "it would be a shame if your good reputation was ruined by some random bad reviews, eh?" and removes bad reviews for companies that hand over the dough :)
I've worked at lots of employers who ask current employees for positive Glassdoor reviews shortly after a disgruntled former employee writes a bad review.
I wouldn't trust anything on that site. The positive reviews are written under duress and the negative reviews have an axe to grind.
the tone on glassdoor has shifted a lot since they discovered HR departments and recruiters as their main (only?) client base.
> ... It's also free to claim your employer account. After that, Glassdoor costs $249 to $600 per month depending on how many jobs you want to post and what specific features you want to add (again, the premium service costs more). -- (probably better sources this is just the top google result) https://fitsmallbusiness.com/glassdoor-vs-indeed/