Here’s a tool for evaluating how your resume compares to an online job posting: Jobscan. In Jobscan’s words, “Unlock more match calculations, skill/keyword comparisons, and matching jobs.”
I discovered it through a comment to a Wall Street Journal career article, though I have not tested it. The free version is limited to 5 comparisons a month and seems a reasonable way to test. Monthly and quarterly-fee versions are also available.
Remember: responding to online job postings is the most traditional and popular method for looking for work, but it’s not the most effective. By employing a strategy is to uncover the hidden–unpublished–job market, you’re likely have better results. Solid mutually beneficial relationships, a focus, and strong self presentation are keys to any job search or career change.
That said, don’t abandon looking at online postings; just don’t restrict your search to that approach.