What is an ATS (applicant tracking system)?
ATS stands for applicant tracking system: software that employers and recruiters use to collect job applications, keep every candidate's details in one searchable database, and move each applicant through the hiring stages.[1][4] Its goal is to let a hiring team manage large volumes of candidates efficiently, with recruiters reviewing applications, searching, and making the hiring decisions.[1][3] Elsewhere the acronym can also mean an automatic transfer switch or an automated trading system.[5]
What an ATS is, in plain words
An applicant tracking system, also called recruiting software, is the employer's inbox and database for job applications. Wikipedia defines it as software that enables the electronic handling of recruitment and hiring.[4] Every resume you submit is collected in one place, parsed, and stored with the rest of the applicant's information, and the system tracks where each applicant is in the hiring process.[2][3][4]
What an ATS does
- Publishes job postings and receives the applications that come in.[4]
- Parses resumes and stores applicant information in a database that recruiters can search.[3][4]
- Lets recruiters search by keywords such as skills, majors, job titles, certifications, and experience.[2] Wikipedia also lists searching and filtering candidate databases among its uses.[4]
- Tracks every candidate's stage, sends automatic messages, and helps schedule interviews.[1][3]
- Provides reporting and analytics.[4] AIChE says organizations rely on these systems to ensure compliance with equal employment opportunity laws.[3]
The goal of an ATS
The goal is organization and efficiency for the employer. Tufts' career center describes an ATS as software that scans resumes for keywords that match the job description and filters out resumes that do not meet the basic requirements.[2] The University of Georgia's career center adds that many employers receive hundreds of applications for every posting and use an ATS to help parse the stacks of resumes and streamline hiring.[11] AIChE says organizations rely on these systems to streamline HR operations and ensure compliance with equal employment opportunity laws.[3] ADP says an ATS does not replace recruiters: it supports them by reducing administrative work so they can focus on evaluating candidates and making hiring decisions.[1] The software is built for the hiring team, which is why your resume has to work for the system and for the person who opens it afterward.
Who uses an ATS
Large employers almost universally. Jobscan's 2026 report, which reverse-engineered Fortune 500 career pages, detected an ATS at 487 of 500 companies (97.4 percent); the rest may run in-house systems.[6] A Harvard Business School Working Knowledge article cites Jobscan for the figure that 99 percent of Fortune 500 firms used applicant tracking software in 2019 (Jobscan's own 2026 report lists 98.8 percent for 2019).[7][6] The same article reports the researchers' own survey, run with Accenture: 63 percent of surveyed employers across the US, UK, and Germany used a recruitment management system, rising to 69 percent among larger enterprises with more than 1,000 workers.[7] Staffing agencies, government bodies, small businesses, and nonprofits use them too.[2]
Common ATS vendors
No single product dominates the whole market. Across the 13,130 companies Jobscan analyzed in 2026, it detected Greenhouse at 19.0 percent, Workday at 17.5 percent, Lever at 15.6 percent, and iCIMS at 14.4 percent. Among Fortune 500 companies, Workday was above 40 percent and SuccessFactors about 12 percent.[6] These are Jobscan's own detection results (career pages for the Fortune 500 figures; job URLs entered into its scanner for the 13,130-company figures), not a census, but they show why one resume-formatting trick rarely works everywhere: employers use different systems and configure them differently.
How an ATS ranks and filters candidates
It depends on the product and on the employer's settings, but four mechanisms come up repeatedly.
- Recruiter search. Recruiters type skills, titles, and certifications into the database. In a recruiter survey run by Jobscan, 76.4 percent said they search and rank candidates by skills from the job description.[6] This is a vendor survey, so read it as indicative.
- Automated ranking, in some products. Some systems compare a resume with the job and produce a relevance rank; AIChE says the ATS parses, sorts, and ranks the resume against the job profile for specific keywords, and university career centers describe systems that read, rank, and score applications against the job description.[3][10][11] Others do not: Greenhouse says its AI does not score or rank applications or decide who moves forward.[8]
- Knockout and auto-reject rules. Employers can set rules. In Greenhouse, auto-reject can be triggered by a candidate's answer to an application question, and the rules are set up by the employer's admins.[9][8]
- Employer-set screening filters. In the Harvard Business School and Accenture study, more than 90 percent of surveyed employers that used a recruitment management system relied on it to make a first cut or rank potential middle-skills (94 percent) and high-skills (92 percent) applicants.[7] Strict filters are one reason qualified people can be missed.
Common misconceptions
"An ATS automatically rejects most resumes."
The evidence is mixed and product-specific. Greenhouse states that its auto-rejection is based on specific rules that recruiters set and control, such as a "no" answer to an application question.[9][8] At the same time, other systems rank applicants and employer filters can screen people out, so it is prudent to write a resume that reads clearly to software and to a recruiter.[7][3]
"You must stuff in keywords."
Greenhouse says the belief that you must stuff an application with keywords to appear in recruiter searches is not the case with Greenhouse, whose system uses AI to suggest related keywords and synonyms for recruiters to search.[8] Using the posting's language where it is true for you still helps recruiters who search by skill, but repeating words you cannot back up does not.
"There is an ATS score the employer sees, and I can check it."
The percentages shown by resume checkers are the checker's own estimate. Jobscan says on its own page that when you submit a resume the ATS does not score it, and that its match rate is a visualization tool for measuring your resume before you apply.[12] Read more in what a good ATS score is and what it does not mean.
"All ATS work the same way."
They do not. The market is split among many vendors and each employer chooses its own settings, so advice that sounds absolute for one product may not apply to another.[6]
What this means for your resume
University career centers give consistent, practical advice: use standard section headings, a simple layout, and common fonts; avoid tables, text boxes, columns, graphics, and headers or footers; put the job's keywords inside achievement-oriented bullets; and do not list skills you cannot prove.[10][11] The aim is not to game the software. It is to make sure the system and the recruiter read your real qualifications correctly.