What is an applicant tracking system (ATS)? A plain guide

An applicant tracking system, or ATS, is the software an employer uses to post a job, collect the applications, and move each person through stages: applied, phone screen, interview, offer, rejected. Greenhouse, Lever, Workday, Ashby and iCIMS are common ones. When you fill in a form on a careers page, you are usually typing into an ATS.

The name covers a lot. Some systems only store and sort applications. Others also schedule interviews, send emails and score candidates. From the outside you cannot tell which features an employer has switched on.

They are widespread. In a 2021 Harvard Business School and Accenture survey of more than 2,250 executives in the US, UK and Germany, 63% of employers said they used a recruiting management system, and 75% of US employers did.^[1]

The part that matters to you: the software does what people at the employer set it up to do. The questions, the filters and the final decisions are theirs.

Sometimes, in specific and documented ways. None of them is a robot disliking your font.

• Screening questions. Greenhouse's own help pages describe a feature called auto-reject: based on an applicant's answer to a question, they are automatically rejected, and the system can send the rejection email too.^[3] Think work authorisation, a required licence, or location. This is the clearest case of software saying no without a person.
• Filters and ranking. In the Harvard survey, more than 90% of employers said they use their system to initially filter or rank candidates. Almost half screened out resumes with a work gap of more than six months, on that basis alone.^[1]
• AI summaries. Newer tools compare your resume with criteria the employer writes. Ashby says its version marks each criterion as met or not met and that "it is up to the reviewer to advance or reject".^[4] That is the vendor's description of its own product.

The quieter problem is volume. If a recruiter sorts 600 applications and reads the top 60, nobody rejected number 400. Nobody reached it either.

So do recruiters actually read resumes? Yes, though not always every one. Applying early, while the pile is small, is one of the few things here that you control.

You will see this number everywhere. There is no study behind it. In 2020 the HR researcher Christine Assaf traced the citations back to Preptel, a company that sold resume-optimisation services and went out of business in August 2013. She found no published research or data to support the figure.^[2]

What has been measured is different. In the Harvard survey, 88% of employers agreed that qualified high-skills candidates are vetted out of the process because they do not match the exact criteria in the job description.^[1] That is employers' opinion of their own filters. It is not a count of resumes, and it is not 88% of applicants.

So the honest version is this. Filters do exclude good people, employers know it, and no one can tell you the rate.

This is common advice rather than measured fact, and we cannot put a number on any of it.

• Keep the layout plain. One column, standard headings such as Experience and Education, real text and not an image of text.
• Use the posting's own words where they are true of you. If the posting says "accounts payable" and you wrote "AP", write both.
• Answer every screening question with care. This is where documented automatic rejection happens.^[3] Read each one twice before you move on.
• Explain gaps. A line such as "2023–2024: full-time caregiver" gives a reader something a bare gap does not. It may not get past a hard filter,^[1] but it helps with every human who reads it.
• Do not stuff keywords. A person reads the resume in the end, and it has to make sense to them.

In a few places. New York City's Local Law 144 says an employer using an automated employment decision tool must have had it audited for bias within the past year, publish information about the audit, and give notices to candidates. Enforcement began on 5 July 2023.^[5] In Ontario, since 1 January 2026, an employer that uses artificial intelligence to screen, assess or select applicants must say so in the public job posting.^[6]

If a posting carries a notice about automated tools, read it before you apply. It is one of the few places an employer tells you how its screening works.

Elsewhere the rules vary and are changing. This is general information, not legal advice.

1. Open your resume as plain text (copy it into a notes app). If it reads in order, software can read it.
2. For the next job you apply to, match five of the posting's terms to things you have actually done, and use its wording.
3. Slow down on the screening questions. Check each answer before you submit.
4. If you know someone at the company, ask them to pass your name on. A person who is expecting your application will look for it.
5. Stop paying attention to "ATS score" claims that quote the 75% figure. Now you know where it came from.