There is a large industry built on fear of applicant tracking systems, and much of what it claims is wrong. These systems rarely auto-reject on a keyword score. What they do is parse your document into fields, and if the parsing fails your experience arrives at the recruiter as gibberish. That is the real risk, and it is a formatting problem rather than a keyword problem.
Use a layout the parser can read
Single column. Standard section headings. No text inside images, no text inside text boxes, no tables holding your job history, no headers or footers containing anything important.
Two-column templates are the most common cause of scrambled output, because the parser reads across the page and interleaves your skills list with your job descriptions.
Submit the right file type
Unless told otherwise, send a Word document or a text-based PDF. A PDF exported from a design tool sometimes contains no selectable text at all, which parses as an empty resume.
Check by opening your PDF and trying to select the text. If you cannot highlight it, neither can the system.
Label sections conventionally
Call them Experience, Education and Skills. Creative headings such as “Where I Have Made an Impact” are parsed as body text, and everything beneath them may be filed under the wrong field or dropped.
Put your name and contact details in the body of the document, at the top, not in a header.
Mirror the language of the posting
This is where keywords genuinely matter, though not in the mechanical way usually described. Recruiters search the database for terms. If the posting says “accounts payable” and your resume says “supplier payments”, you will not appear in that search.
Use the employer vocabulary where it is accurate. Do not list skills you do not have; that is discovered quickly and ends badly.
Spell out acronyms once
Write the full term with the abbreviation in brackets the first time. Different people search for different forms, and covering both costs you four words.
Keep dates in a standard format
Month and year, consistently, for every role. Unusual formats and missing dates confuse the parser and are frequently read as gaps.
Write for the human who reads it next
Once parsed, a person spends a short time scanning. The top third of the first page decides whether they continue.
Put your strongest, most relevant material there. Lead each bullet with what you did and what changed, not with the responsibility you held.
Quantify where you honestly can
Numbers stop the eye. Volume, percentage, time saved, budget, team size, anything measurable. Where you have no figures, be specific instead: name the system, the scale, the outcome.
Do not fill it with tricks
Hidden white text stuffed with keywords is detectable, and every recruiter has seen it. It converts a maybe into an immediate no and occasionally into a note on your file.
Test it before you rely on it
Copy your resume, paste it into a plain text document, and read what comes out. That is approximately what the system sees. If it is unreadable there, fix the layout before sending another application.