What an ATS actually does
It takes your file, extracts the text, and tries to work out which part is your name, which is an employer, which is a date range. Recruiters then search that database. If parsing fails, your record is incomplete or garbled — that is the real failure mode, not a rejection algorithm.
This reframes the whole problem. You are not trying to beat a filter. You are trying to be machine-readable.
What breaks parsing
Layout, almost always. Anything that makes the text hard to read in a straight line is a risk.
- Contact details inside a header or footer, which some parsers never read
- Text inside images, including a name rendered as a logo
- Multi-column layouts, which can interleave into nonsense
- Tables used for layout rather than data
- Unusual section names — "Where I've Been" instead of "Experience"
- Dates written inconsistently between entries
What doesn't matter as much as people claim
Keyword density is the big one. Stuffing a skills section with every term from the posting does not raise a score, because there usually is no score — and a human reads the page immediately afterwards.
Fonts, colour, and a tasteful accent are fine. So is a sidebar, provided the underlying text order still makes sense when read linearly. The test is not "does it look plain" but "does the text extract cleanly".
Do use the words in the posting
Not as stuffing — as accuracy. If the posting says "incident response" and you wrote "on-call", a recruiter searching the database for the former will not find you. Use the vocabulary of the industry you're applying into, where it honestly describes what you did.
The honest constraint matters. A term on your resume is a term you can be asked about.
Send a PDF unless told otherwise
Modern systems parse PDFs fine, and a PDF is the only way to guarantee the recruiter sees the layout you designed. Send .docx only when the application explicitly asks for it.
One caveat: the PDF has to contain real text. A scan or an exported image looks identical on screen and extracts as nothing at all.
What an applicant tracking system is, plainly
It is a database with a workflow attached. When you apply, the system stores your file, extracts text from it, tries to split that text into structured records — your name, contact details, and a title/employer/date triple for each job — and files you against the requisition. Recruiters then search, filter and move candidates through stages inside it.
Workday, Greenhouse, Lever, iCIMS, Taleo, SuccessFactors and Ashby are the ones you will meet most often. They differ in quality, and the older enterprise systems are meaningfully worse at parsing than the newer ones, which is most of why advice about them is inconsistent — people are describing different software.
The important part is what it is not. It is not an AI judging your worth, and it does not reject applications on a score. It is filing software. The damage it does is passive: a bad parse produces an incomplete record, an incomplete record ranks badly against the requisition, and a badly-ranked application is never opened by the person who would have liked it.
Resume checkers and scores
Tools that give your resume a score out of a hundred are checking a list of mechanical properties: is the text real, is the layout single-column, are the section headings recognisable, do the posting's terms appear, is there a date on every role. All of that is genuinely worth knowing, and it is roughly the same list as this page.
What the score is not is a prediction. No checker has access to the employer's actual system, the requisition's weighting or the recruiter's judgement, so a number attached to your resume is a formatting checklist expressed as a percentage. Treat a low score as a prompt to find the specific problem, and ignore the number itself.
Be sceptical of any checker whose result is a paid rewrite. The failure modes it reports are all things you can fix in ten minutes once you know what they are, and the copy-paste test on your exported PDF finds the serious ones for nothing. The review here reports what is structurally weak — missing outcomes, buried terms, sections in an order that works against you — rather than issuing a grade.
