What is actually testable about a resume
Any tool offering a pass rate or a compatibility percentage is describing something it cannot see.
Why the pass rate is fiction
Applicant-tracking systems are products that employers buy and then configure. The screening rules, required fields and knockout questions are set by whoever set them up, so the same product behaves differently at two companies.
Nobody outside a vendor can see that configuration, which makes "87% ATS compatible" a number with nothing behind it. What can be tested is the document: whether the text comes out, whether the sections are recognisable, whether the dates are unambiguous.
The failures that actually lose content
Contact details in a header or footer. In several formats these sit outside the document body and are among the most common causes of a missing phone number.
Text inside an image. An image of text contains no text. Without optical recognition it is recovered as nothing at all.
Floating text boxes. Content in a box sits outside the main flow and is frequently not recovered.
Two-column layouts. Some extractors read across the columns rather than down them, which interleaves unrelated lines. Others handle it correctly, and you cannot tell which you are facing.
Ambiguous dates are the cheapest fix
"03/04/24" is March 4th to an American reader and 3rd April to most of the world. No parser can resolve it from the string, and nor can a human.
"Mar 2024" reads identically everywhere, takes the same space, and removes the problem entirely.
Keywords are concepts, not strings
Matching should treat "K8s" and "Kubernetes" as the same requirement. It should not treat AWS and Azure, or React and Angular, as interchangeable — a candidate told those are equivalent walks into a technical conversation believing they are covered.
And where a term sits matters. A skills list costs nothing to extend, which is exactly why it persuades nobody. The same term inside a described achievement has scale, context and a result.
Do not let anything write it for you
Every line on a resume is something an interviewer can ask about. A generated achievement is a question you cannot answer, and a fabricated metric is a lie in a document you put your name to.
Where something is missing, the useful response is a question — what did you do, at what scale, with what result — not a sentence to paste.
Which file format
Use the format the employer asks for. Where none is specified, DOCX is the compatibility-oriented default and a text-based PDF preserves appearance. What matters more than the choice is that the text is selectable: if you cannot select and copy it, neither can anything else.