Best AI Detector
Seven detectors compared on the things that can be verified — who is allowed to use each one, what it costs, what the free tier covers, and what its accuracy claim actually rests on. The two your university is most likely to run, Turnitin and DrillBit, are not available to students at all, which changes what “best” means if you are the one being scored.
Why No Two Accuracy Tests Agree
Every detector claims 99% accuracy. Independent tests put the same tools 10 to 20 points lower, and the rankings flip depending on who ran the test. One study has Originality.ai at 97%; another has it at 31.7%. The number changes with the text: raw output or edited, long or short, written by a native speaker or not.
What This Comparison Checks Instead
Compare the checkable facts instead. Who can use the tool, what it costs, what the free tier covers, and — for each accuracy figure — who produced it and on what text. Those are printed on each vendor’s own pages and were read on 10 November 2026. The one peer-reviewed study of commercial detectors is quoted with its exact numbers.
How it works
- Find out which detector your institution runs — that is the only score with consequences
- Use a free checker to see which of your sentences read as generated, not to predict the official score
- Read every accuracy claim with its author attached: vendor-run tests favour the vendor
- Weigh the false-positive rate, not the detection rate, if you write in English as a second language
- Keep drafts and version history; they settle a dispute that a score cannot
Seven detectors, side by side
Figures as printed on each vendor’s site on 10 November 2026, except where the row names another source. “Institutions only” means a student cannot buy or run the tool; it is sold to universities and the report goes to staff.
| Tool | Who can use it | Free allowance | Paid from | Accuracy claim, and what it rests on |
|---|---|---|---|---|
| ASimplify Detect (ours) | Anyone | Limited checks every day, no card | Pro Lite $10/mo: unlimited AI Detect | We publish no percentage. No neutral benchmark on student essays exists, so any figure we printed would be our own test. |
| GPTZero | Anyone | 10,000 characters a scan without an account; a free plan GPTZero lists at 10,000 words a month | Premium from $12.99/mo (GPTZero’s own October 2026 listing) | “99.9%” headline; on the RAID benchmark GPTZero reports catching 95.7% of AI texts and wrongly flagging 1% of human ones. Vendor-run. |
| Turnitin | Institutions only; students cannot see the AI report | — | — | Under 1% document-level false positives where more than 20% is flagged; about 4% at sentence level. Self-reported. |
| DrillBit | Institutions only; 2,800+ claimed, 1,150+ in India through ShodhShuddhi | — | — | No number published. Describes its output as “indicators and probability-based insights” that “should support human judgment rather than replace it”. |
| Originality.ai | Anyone | 10,000 words once (100 credits) | Pro $14.95/mo, or $12.95/mo billed yearly; 1 credit = 100 words | One of the seven detectors in Liang et al. (2023), which averaged 61.3% false positives on essays by non-native writers. |
| Pangram | Anyone | 7-day trial, no ongoing free tier | Individual $20/mo for 300,000 words; Professional $65/mo | Cited by several reviewers for low false positives. Vendor and reviewer claims; not peer-reviewed on student essays. |
| ZeroGPT | Anyone | 15,000 characters a check | Paid tiers exist; prices are not printed on the main page | Also among the Liang et al. seven. Appears with the highest false-positive rate in several round-ups. |
What each one is for
ASimplify Detect
For checking your own draft before anyone else does. It scores sentence by sentence inside the document, so the output is a list of the passages that read as generated rather than a single percentage, and the humanizer and citation tools sit beside it for the fix. Free checks every day without a card; unlimited on Pro Lite at $10 a month. We make it; read the accuracy column above before trusting this paragraph.
GPTZero
The most used free checker and the one with the most public benchmark data. Scans up to 10,000 characters without an account. Its headline figure is 99.9%; the RAID result it cites is 95.7% of AI text caught with 1% of human text wrongly flagged, and the page says the model is trained to hold false positives on second-language writing to 1%. All of that is GPTZero’s own testing. Useful for a second opinion, not for predicting Turnitin.
Turnitin
The detector most universities outside India actually run, and one you cannot use yourself. Scores between 1% and 19% are shown as an asterisk, not a number, “to avoid potential incidence of false positives”. The report goes to instructors only. Turnitin says the percentage “should not be used as the sole basis for action” and added detection for humanizer-processed text in late 2025. The guide to what the percentage means covers the rest.
DrillBit
The default for the Ministry of Education’s ShodhShuddhi programme since late 2023 and the detector behind most AI reports in Indian higher education. Its AI report labels each sentence AI or Human with a confidence figure and sorts the document into High AI, Human-Written and Mixed/Uncertain. It publishes no accuracy number. Institution-sold; students see what their department shares. See what a DrillBit AI percentage means.
Originality.ai
Built for publishers and agencies, priced by credit at 100 words each. The free 10,000 words are one-time, not monthly. It was one of the seven tools in the only peer-reviewed detector study, which is the most important thing to know about its false positives on non-native writing.
Pangram
The tool most often named by reviewers for low false positives, including on second-language essays. The evidence is reviewer tests and the vendor’s own, not peer review. No free tier beyond a seven-day trial; $20 a month for 300,000 words, which is far more than a student needs.
ZeroGPT
Free for 15,000 characters a check, which is why it is the one students paste into first. It was among the Liang et al. seven and shows up with the highest false-positive rate in several round-ups. Fine for a rough look; a poor basis for any decision.
The figures that are actually verifiable
Two sources are checkable rather than self-reported marketing.
Peer-reviewed: Liang et al., Patterns 4(7), 2023
Seven detectors — Originality.AI, Quil.org, Sapling, OpenAI’s classifier, Crossplag, GPTZero and ZeroGPT — were run on 91 TOEFL essays by non-native English speakers. On average 61.3% were wrongly flagged as AI; 19.8% were flagged by all seven. Improving the essays’ word choice with an LLM cut the false-positive rate to 11.6%, and simplifying the vocabulary of native speakers’ essays made flagging more likely. Turnitin and DrillBit were not tested.
Self-reported: Turnitin
Under 1% document-level false positives where more than 20% of a document is flagged, measured on 800,000 pre-GPT papers; about 4% at sentence level, revised up from an initial under-1% claim; 54% of false-positive sentences sit directly beside a genuinely AI-written one. Scores from 1% to 19% are hidden behind an asterisk for that reason. The report runs on long-form English prose only and is not shown to students.
Everything else on the first page of this query — including the figures in our table above — is a vendor describing its own product.
If you are the one being scored
Most of this comparison is written for people choosing a detector. If you are a student, you are not choosing one — one is being run on you. That changes what is useful.
- You usually cannot see your own report. Turnitin’s AI indicator is instructor-only by design; DrillBit’s goes to the institution. A free checker shows you which sentences read as generated; it does not show you the official number.
- The official number has no published cut-off. Turnitin sets none, and says the percentage is a starting point for a conversation. Your course policy is the document that matters.
- Short, formal, uniform sentences get flagged. That is a property of the classifier, not of your honesty. Literature reviews and second-language writing are hit hardest; see what to do if you were flagged on your own work.
- If you did use AI on a passage, fix the passage. A Turnitin or DrillBit report tells you which ones.
Where this one fits
We make a detector, so the same conflict applies here as to every other page on this query. ASimplify Detect is for checking your own draft inside the document before submission, with the fix one click away. It is not an authority on whether anyone cheated, it cannot predict Turnitin’s or DrillBit’s score, and we do not print an accuracy percentage because the only honest one would be our own test on our own text. The free daily checks are so you can see what it flags on writing you know you wrote.
Want the method, not just the tool?
How to Humanize ChatGPT Text (Without Making It Worse) — Why AI text reads the way it does, how detectors actually work, why they flag innocent students — and the rewriting moves that make writing genuinely yours.
Try it on your own document
Write, cite, humanize and check your AI score in one editor. The free plan includes limited AI chat and AI detection each day, plus three humanizer runs — no card needed.
Open the editor →