What Is an ATS? How Applicant Tracking Systems Work (2025)

Before a human reads your resume, software does. That software is called an ATS — Applicant Tracking System — and it's the reason most applications end before they begin. Here's exactly how it works and what you need to do to get through it.

What is an ATS?

An ATS (Applicant Tracking System) is software that companies use to receive, organize, and filter job applications. When you submit an application on a company's job portal — or through LinkedIn, Indeed, or any job board — your resume flows into an ATS before any recruiter sees it.

The ATS parses your resume into structured data: name, contact info, work history, education, skills. It then scores that data against the job's requirements and filters applications by score. Recruiters see a ranked list — not your resume as you designed it.

Companies with 50+ employees almost universally use ATS. The most common systems are Workday, Greenhouse, Lever, iCIMS, Taleo, and BambooHR. Each has its own parsing quirks, but they all operate on the same core logic.

Why 87% of resumes get rejected before a human reads them

The 87% figure comes from HR data on application rejection rates at large companies. The reasons fall into two categories:

1. Formatting that breaks parsing

ATS systems parse text from top to bottom in a single column. Two-column layouts, text boxes, tables, and headers placed in the page margin confuse parsers and produce garbled or incomplete records. A candidate with perfect qualifications whose resume parses incorrectly may show up with no work history, no skills, or scrambled dates — and score below the threshold.

2. Missing keywords

ATS systems keyword-match your resume against the job description. If the job requires "project management" and you wrote "project coordination," you may miss the match. If you have experience with a required skill but never wrote the exact term the JD uses, you score lower — even though you're qualified.

How ATS scores your resume

The scoring process varies by system, but the core logic is consistent:

1. Parse: The ATS extracts text from your document and classifies it into categories — work history, education, skills, contact info.
2. Match: The extracted data is compared against required and preferred qualifications in the job description. Keyword matches are weighted.
3. Score: A composite score is generated based on match rate, years of experience, education level, and other factors the recruiter configured.
4. Rank: All applications are ranked by score. Recruiters typically review the top 10–20% of applicants.

Recruiters rarely set a hard cutoff score manually — instead, they work through the ranked list until they have enough qualified candidates to schedule. If you're not in the top of the ranked list, you're unlikely to be reviewed regardless of your qualifications.

5 rules for passing ATS screening

The fastest way to check your resume's ATS score

The quickest way to know if your resume passes ATS is to test it. Zari's free ATS checker parses your resume the same way ATS software does and returns a detailed score — formatting errors, keyword gaps, section issues — with specific fixes for each.

If you want to go deeper, Zari's AI resume writer rewrites every weak bullet with ATS-targeted language so you don't just pass the filter — you rank near the top of it.