Why AI resume detectors do not work

They measure predictability, not authorship — which flags careful writing and second-language writing hardest. What recruiters actually notice instead, and why we have not built one.

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There is no reliable way to detect whether a resume was written with AI, and the tools that claim to do it are wrong often enough to be dangerous. If you are searching for one because you are worried your own resume will be flagged, the useful news is that the flag is mostly not real. If you are a recruiter looking for one, the useful news is that you will spend money to reject good candidates.

Why detection does not work

An AI-text classifier does not detect AI. It detects statistical predictability — roughly, how unsurprising each word is given the words before it. Language models produce predictable text, so predictable text scores as AI.

The problem is that plenty of human writing is also predictable, and the most predictable human writing in existence is a professional document written in a conventional register by someone being careful. Which is to say: a resume.

It gets worse the further you are from the tool’s training distribution. Non-native English writers are flagged at substantially higher rates than native writers, for the straightforward reason that careful second-language prose uses common constructions and a smaller vocabulary. That is the same population these tools are least equipped to judge and most likely to penalise.

And a resume is short. Classifiers are unreliable on long documents and essentially arbitrary on a two-line bullet point. Most of what these tools say about a resume is noise presented as a percentage.

What the percentage means

Nothing you can act on.

A detector that reports “92% AI” is not saying there is a 92% chance the text is AI-generated. It is reporting a score from an internal model on a scale it defined, with no published error rate on your kind of document. Two detectors run on the same resume routinely disagree completely, which is by itself sufficient evidence that at most one of them can be right.

The vendors mostly know this. Read the fine print and you will usually find language saying results should not be used as the sole basis for a decision — on a product whose entire purpose is being the basis for a decision. OpenAI shut down its own detector in 2023 because the accuracy was not there. The people with the most information about how these models write concluded that identifying their output was not a solvable problem.

Does the ATS check for AI?

Almost always no, and it is worth separating the two systems people merge here.

An applicant tracking system is a database with a parser in front of it. Its job is to turn your PDF into structured fields and let a recruiter search them. The large ones — Workday, Greenhouse, Lever, Taleo, iCIMS — do not ship an AI-authorship classifier, and the reason is practical rather than principled: a false positive on that check is a rejected candidate the employer can be asked to justify, and no vendor wants to own that liability on a signal this weak.

What some employers do have is a separate screening layer bolted on after the ATS, and a handful of those advertise an AI-detection score. Treat it as the same unreliable number described above, because it is produced the same way. The realistic exposure for most applicants is a human who has read four hundred resumes and finds yours generic — not a machine flag.

Two places where a genuine check does exist and is worth knowing about: take-home assignments, which increasingly carry an explicit AI-use policy, and written application questions in graduate schemes, some of which are run through detectors. Both are cases where you are being asked to demonstrate your own writing, and both are better handled by reading the stated policy than by guessing at it.

What replaces detection

Experienced readers do not identify AI. They identify emptiness — claims with no numbers, six bullets of identical construction, a summary about qualities instead of facts, a metric that cannot survive one question in the interview.

The important thing about that list is what kind of list it is: every item on it is a writing quality problem, not an authorship problem. A human can produce all of them unaided, and an AI-assisted resume with real numbers and specific work in it triggers none of them. Which is why no detector is needed to catch the thing people are actually worried about, and why no detector would catch it if you built one.

The full list, and what to do about each one, is on can recruiters tell if your resume was written by AI — that page is about the person reading; this one is about the tools.

If you are worried about being flagged

Do not try to defeat a classifier. “Humanising” tools that shuffle synonyms and inject odd phrasing make the writing worse, and worse writing is a real cost against a hypothetical one.

Do this instead, which improves the resume regardless:

  • Put a number in most bullets — scale, volume, time, money, people. Specificity is the opposite of generated prose and it is also what gets you interviews.
  • Use the words your industry uses, including the unglamorous ones. Name the actual tools, systems and teams.
  • Keep the things that are odd about your history. A model smooths them out; they are frequently the most interesting thing on the page.
  • Read it aloud. Anything you would not say in a conversation about your own work is the part that reads as generated.

More on getting numbers into bullets in how to write resume bullet points.

If you are a recruiter

Screening on a detector score means rejecting candidates on a measurement with an unpublished error rate that is known to be biased against second-language speakers. That is a discrimination exposure attached to a tool that does not work.

The signal you actually want is already available and does not require a product: ask one specific follow-up question about a specific claim. Real work has detail behind it. That interview question separates candidates far more reliably than any classifier, and it is defensible if anyone ever asks how you decided.

Where this site fits

We do not sell an AI detector and we are not going to. We could ship one this month — it is a small feature and it would rank for the query that brought you here. It would also print confident percentages we know to be unreliable, and a scoring tool we cannot stand behind is worth less than no tool.

What we do run is a free checker that reports what a parser extracts from your PDF and grades eight measurable categories — things like whether your dates parsed, whether your bullets carry numbers, whether your headings survived. Every one of those is checkable, which is the difference. The AI writing help here proposes changes you approve or reject one at a time, and it asks you for the number rather than inventing one, because an invented metric is the failure mode that actually loses people jobs.

Related: what recruiters think about AI-written resumes.

Common questions

Does an ATS check for AI-generated resumes?
Almost never. Workday, Greenhouse, Lever, Taleo and iCIMS parse your file into searchable fields; none of them ships an AI-authorship classifier, because a false positive on that signal is a rejected candidate the employer would have to justify. A few employers bolt a separate screening tool on afterwards, and those are as unreliable as any other detector.
Can an AI detector tell if my resume was written by AI?
Not reliably. These tools measure how predictable text is, not who wrote it — and a resume is short, formulaic and written in a house style, which is the exact profile that produces false accusations. Careful writing and second-language writing get flagged hardest.
What does an AI detection percentage actually mean?
It is the tool's estimate of how predictable your wording is, presented as a confidence figure it has not earned. An '87% AI' result does not mean there is an 87% chance a model wrote it. On a document as short as a resume the number is close to noise.
How do I avoid being flagged as AI?
Do not try to defeat the classifier — the tools that shuffle synonyms to beat one make the writing worse and the result reads as evasive. Write specifically instead: real numbers, real systems, work you can describe in an interview. Specific writing is both less predictable and better.

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