Look for job aggregators like Adzuna, Indeed, etc, which scrape all jobs on the web. When you see results, it should be easy to work out which jobs are posted by recruiters, and which have been posted directly by the company.
In my (massively biased) experience, you are better off applying for a position when you've been put forward by a recruiter:
* The recruiter knows what the client's salary range is, and wants you to get paid as much as possible (as the role is commission based) - they'll be able to make sure you're getting a good deal out of the client
* The recruiter is a professional sales person, and will chase the hiring manager for feedback, technical interviews, etc etc, in a way that as a direct candidate you'll come across as too pushy if you do yourself
* The recruiter will genuinely have a good view of other similar jobs you may not have found that you'd be a good match for.
* The recruiter will get much much more candid feedback about you than you'll ever get directly from the client
... and a whole bunch of other factors.