Can the software actually read your file? A specific answer.
Most of this category sells "pass the ATS", which is not a real thing. An applicant tracking system is software each employer configures with their own variables; there can be several screens for one job, and nobody can promise you get through them.
What can be answered is narrower and more useful: can a text parser read this file at all? Are your name, email, phone, employers, titles and dates extractable? Does your history come apart into separate roles, and do your headings use words a parser recognizes? Those are facts about a document, and we check twelve of them.
Passing all twelve is worth having and it is only half the picture. A perfectly readable resume still gets passed over when it does not answer the job in front of it, and that half cannot be judged from your file alone: it needs a posting to measure against. Getting your material to line up with a specific posting, in the words that posting uses, is where applications are actually won, and it is the thing we do next.

The one you have actually been sending. No account, no card, nothing to sign up for.
We pull the text out of your file and sort it into the fields a tracking system looks for. Then twelve fixed rules check what came out, not an opinion, and each one says what it found. It takes about thirty seconds.
Each check names the problem in plain language and what fixes it. You also see how many of them a rebuild would fix for you; the ones we cannot invent (a missing phone number, say) stay yours to fix.
Continue into the builder and the fixable problems are gone in the rebuilt version. We already read your file, so you skip the upload and the wait that comes with it.
These are constraints we chose, not gaps we haven't got to.
There is no score out of 100 here and there never will be. A number teaches you to chase the number, and it implies a precision about a hiring manager that nobody has.
This half is about the file. How well your material matches one specific posting is a different question, needs the posting as an input, and gets answered in bands rather than a number: see Targeted Applications, which is where that work happens.