Free AI Content Detector for ChatGPT, Claude & Gemini
Paste your text and instantly see what's AI-generated, human-written, or AI-refined — with a sentence-by-sentence breakdown and honest confidence scores. No sign-up, no word limit.
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Built for the people who check text every day
Universities
academic integrity
Newsrooms
editorial desks
SEO Agencies
content QA
Publishers
submission screening
EdTech
learning platforms
What is an AI Content Detector?
An AI content detector — also called an AI checker — reads a piece of text and estimates how likely a machine wrote it. It hunts for the patterns large language models leave behind and works out whether the writer leaned on a tool like ChatGPT, GPT-5, Claude or Gemini. Most detectors also over-flag non-native English writers as a side effect of how they work — QuillBotAI Pro is built specifically to correct for that.
It is not a plagiarism checker. Plagiarism tools ask whether text was copied from somewhere else. A detector asks something different: does this read like a person typed it, or like a model predicted it? Teachers, editors, SEO teams and hiring managers use that answer every day to keep the content in front of them honest.
The tell is predictability. A model picks the safest next word every time, so its writing comes out smooth, even, and a little too consistent. People do not write that way — we ramble, then snap to a three-word sentence, reuse a favourite phrase, change our mind mid-paragraph. QuillBotAI Pro scores those signals line by line instead of handing you one blunt verdict.
- Not a plagiarism checker — it reads how text was produced
- Sentence-level output, not a single pass/fail score
- Calibrated so non-native English writing isn't mistaken for AI
- Built for the common case: part human, part AI-refined
How Does the AI Detector Work?
Paste your text, run the scan, read the breakdown. No account, no word cap, no setup.
Paste or upload your text
Drop in an essay, article, email or cover letter — or upload a file. Aim for at least 25 words; short snippets don't give the analysis enough to work with.
Run the scan & review
Hit Detect AI and get a 0–100% score in seconds, plus a sentence heatmap. Click any flagged line to see the exact signal that tripped it — not just a number.
Review with confidence
Read through the flagged lines and decide for yourself what needs a second look. Everything runs in your session and is discarded the moment you're done.
Four signals, measured simultaneously
Perplexity
How predictable each word choice is. AI takes the safe option; people don't.
Burstiness
Variation in sentence length. Human writing swings; AI stays flat.
Vocabulary diversity
The spread of word choices. Machine text clusters in a narrow band.
Model fingerprinting
Phrases each model overuses — 'it's important to note', 'delve into', 'in conclusion'.
Supported AI Models
Every model leaves a slightly different statistical signature. We calibrate against the major ones and re-check as new versions ship — detection coverage decays the moment a new model lands.
ChatGPT Detector
GPT-4o · GPT-5
OpenAI's models favour balanced, well-structured paragraphs and a recognisable set of transition phrases. ChatGPT output is the most widely studied and the easiest to catch on clean, unedited text.
- Most-studied fingerprint
- Strong on essays & articles
- Catches GPT-5 phrasing shifts
Why Choose QuillBotAI Pro?
Most detectors lock you behind a word limit, hand you one number with no explanation, or flag every non-native English writer as a robot. Here's what we do instead.
Sentence-level heatmap
See exactly which lines look AI-written — green for human, amber for mixed, red for machine — not one blunt percentage for the whole document. It's the single most useful thing a detector can show you, and most free tools don't.
Genuinely unlimited & free
No 1,200-word cap. No daily scan limit. No account. No paywalled 'premium' verdict. The full tool — heatmap, four-vector breakdown, everything — costs nothing.
Fair to non-native English
Most detectors flag English written by Urdu, Hindi, Spanish or French speakers as AI, because plain vocabulary and regular sentence structure look 'machine-like' to a naive check. Our analysis weighs multiple signals per sentence instead of penalizing plain English alone, so real people are less likely to be falsely accused.
Catches humanized text
Paraphrasers change surface wording but usually leave behind uniform rhythm and predictable phrasing. The detector looks for those leftover traces — and when text has been heavily rewritten, it says so with a lower confidence score instead of pretending to be certain.
Zero data retention
Your text is processed in memory and discarded the moment the scan finishes. Nothing written to disk, no logs, no training on your input. GDPR and CCPA compliant.
Who Uses This Tool?
AI detection isn't only an academic-integrity thing anymore. The people checking text every day come from a much wider mix.
Teachers & professors
Sanity-checking submissions before a hard conversation — using highlights to start a discussion, not issue a verdict.
Editors & publishers
Screening freelance drafts and guest posts so AI-spun filler doesn't slip into the pipeline.
SEO & content teams
Auditing writer output and keeping thin AI content off pages that need to rank after Google's spam updates.
Recruiters & HR
Reading cover letters that increasingly come straight out of a chatbot — and spotting the generic ones fast.
Multilingual writers
Non-native English writers confirming their own work won't get falsely flagged by a stricter detector elsewhere.
Students & self-checkers
Running their own drafts to see what reads as machine-written before someone else does it for them.
How Writers, Teachers & Editors Use It
Typical ways people put the sentence-level heatmap to work in day-to-day checking.
“The sentence highlighting is what sold me. Instead of accusing a student off one number, I can point to the exact lines that read as AI and have a real conversation.”
Marwa R.
University lecturer
“I screen about thirty freelance drafts a week. This catches the spun, humanised stuff other tools waved through — and scanning unlimited text without a paywall is the whole reason I switched.”
Daniel K.
Content editor
“Other detectors kept flagging my own writing as AI just because English isn't my first language. This one didn't. That alone earned my trust.”
Priya N.
Non-native English writer
“I use the heatmap to decide what needs a rewrite before it goes live, line by line instead of guessing off one score.”
Tomás L.
SEO consultant
“I run my own drafts through it before submitting, mostly to catch sentences that sound too generic. It's basically a second read from a very picky editor.”
Aisha M.
Graduate student
“Cover letters straight out of ChatGPT all read the same after a while. This confirms the gut feeling fast.”
Greg P.
Recruiter
“The sentence highlighting is what sold me. Instead of accusing a student off one number, I can point to the exact lines that read as AI and have a real conversation.”
Marwa R.
University lecturer
“I screen about thirty freelance drafts a week. This catches the spun, humanised stuff other tools waved through — and scanning unlimited text without a paywall is the whole reason I switched.”
Daniel K.
Content editor
“Other detectors kept flagging my own writing as AI just because English isn't my first language. This one didn't. That alone earned my trust.”
Priya N.
Non-native English writer
“I use the heatmap to decide what needs a rewrite before it goes live, line by line instead of guessing off one score.”
Tomás L.
SEO consultant
“I run my own drafts through it before submitting, mostly to catch sentences that sound too generic. It's basically a second read from a very picky editor.”
Aisha M.
Graduate student
“Cover letters straight out of ChatGPT all read the same after a while. This confirms the gut feeling fast.”
Greg P.
Recruiter
Frequently Asked Questions
Everything you need to know about the detection engine, privacy, fairness, and what the AI detector can and can't tell you.
Try the Free AI Detector Now
Paste any text and get a sentence-by-sentence read in seconds. Free, unlimited, private.