Applicant tracking systems vary by vendor and employer.
What an ATS is
Workday describes an applicant tracking system as a central database for candidate information, used to organize, search and move candidates through a hiring workflow (Workday). That is a vendor overview, not a count of how many employers use one or a benchmark of how they behave.
What vendors document about screening and parsing
Vendors document the variation. Greenhouse says that when a resume cannot be parsed, it can stay attached to the candidate record and the recruiter enters the details manually (Greenhouse Support). Workday notes that parsing "results can vary based on resume format and order of words" (Workday Documentation). Greenhouse also lets an employer configure automatic rejection based on an applicant's answer to a specific application question (Greenhouse Support).
What research on AI in hiring covers
- A field experiment with nearly half a million jobseekers on one online labor platform found that those given algorithmic writing assistance were hired about 8% more often (van Inwegen, Munyikwa and Horton). It tested writing help on that platform. It did not test ATS optimization or any resume checker.
- A 2025-26 simulation in which the same LLM both wrote and screened resumes across 24 occupations reported that the model favored resumes it had written (Xu, Li and Jiang, arXiv). It is a simulation and says nothing about how deployed ATS rank or reject real applicants.
What this means for your resume
Because parsing and rules differ, plain advice holds up best: use a simple layout with conventional section headings, answer application questions accurately, and tailor your wording to the posting only where it is true of your experience.
FilteredIn's free resume check lets you paste or upload a resume (PDF or TXT) and, optionally, a job description. It returns feedback on content and keywords. A score is product feedback to help you revise; it is not a prediction of any employer's ATS or hiring decision. Try the free resume check.
For more on how screening works, see our related article on ATS rejection.
Sources
- Workday, Applicant tracking system overview
- Greenhouse Support, Unsuccessful resume parse
- Greenhouse Support, Auto-reject
- Workday Documentation, Concept: Resume Parsing
- van Inwegen, Munyikwa and Horton, algorithmic writing assistance field experiment (arXiv:2301.08083)
- Xu, Li and Jiang, AI self-preferencing in hiring (arXiv:2509.00462, revised June 2026)