What Is an ATS? A Complete Guide to Applicant Tracking Systems

If you've applied for jobs online and wondered why you never heard back, there's a good chance an Applicant Tracking System (ATS) filtered out your resume before a human ever saw it. In this guide, we explain what an ATS is, how it works, and — most importantly — how to make sure your resume gets through.

What Is an ATS?

An Applicant Tracking System (ATS) is software that employers use to manage the recruitment process. When you apply for a job online, your resume is parsed and stored in the ATS. Recruiters then search the database for candidates whose resumes match specific keywords and criteria.

Most large companies and many small-to-medium businesses use an ATS. In fact, over 90% of Fortune 500 companies rely on ATS software to handle the high volume of applications they receive. If you're applying to jobs online, your resume is almost certainly being processed by an ATS.

How Does an ATS Work?

When your resume is submitted, the ATS does the following:

• Parses your resume — extracts text from your file and converts it into a structured profile
• Searches for keywords — looks for specific skills, qualifications, and experience relevant to the role
• Scores and ranks — assigns a match score based on how well your resume aligns with the job description
• Filters candidates — automatically rejects resumes that fall below a certain threshold

Why Do Resumes Get Rejected by ATS?

Common reasons include:

• Wrong file format — some ATS software struggles with certain file types. PDF and DOCX are generally safe choices.
• Missing keywords— if your resume doesn't include the right skills and phrases from the job description, the ATS may rank you low.
• Poor formatting — tables, columns, and graphics can confuse ATS parsers, causing them to extract text in the wrong order.
• Lack of standard section headers— the ATS looks for sections like “Work Experience,” “Education,” and “Skills.” If your resume uses creative headers, the ATS may not recognise them.

How to Make Your Resume ATS-Friendly

1. Use a standard format. Stick to PDF or DOCX. Avoid tables, images, and complex layouts.
2. Include relevant keywords. Carefully read the job description and incorporate the same skills and phrases into your resume.
3. Use standard section headings.“Work Experience,” “Education,” “Skills,” and “Certifications” are widely recognised.
4. Keep it simple. Avoid headers/footers with important information, columns, and text boxes that might confuse parsers.
5. Run a health check. Use a tool like HirePilot to test your resume before submitting it.

Free vs Paid ATS Tools

Many ATS checking tools charge a subscription. HirePilot offers a free resume health check with no limits. For advanced features like job match analysis and AI rewrites, the Job Search Pass is a one-time payment with no auto-renewal.