Best AI Detectors (2026): 5 Checkers Compared, and How to Read a Score

Short answer: the best AI detectors in 2026 are Pangram for teachers and editors who want results inside Google Docs or their LMS ($20 a month, 7-day trial), Scribbr AI Detector for a free, no-account first pass on up to 1,200 words, It's AI for the cheapest paid plan and schools that pay per student ($9 a month, or $5 per student a year), Originality.ai for publishers who also want plagiarism checks on the same credits ($14.95 a month), and GPTZero for school teams. None of them can prove a text was written by AI. Every one gives a probability, and the vendors say so themselves. Updated November 3, 2026.

How we checked: plans, prices and limits come from each vendor's own pricing, help and terms pages, read November 3, 2026 (Pangram's pricing on November 1 and again today, Scribbr's on November 2). We did not run our own accuracy test, so this guide compares plans, prices and features, not detection quality. Where we quote accuracy figures, we say who published them; most come from the vendors. Copyleaks and Turnitin pages blocked our reader today, so we list no prices for them.

Every detector here works the same way at heart: a model estimates how likely it is that a passage was produced by a language model. That estimate can be wrong in both directions. It's AI's own terms describe results as probabilistic and say they are not definitive proof. Scribbr's detector page says no detector is fully accurate and recommends scanning longer passages. Pangram's model does not score texts under 50 words at all.

The disagreements between vendors show how soft the numbers are. Scribbr's own comparison of 12 detectors put its free tool at 78% accuracy; a Pangram test from January 2026 found the same free tool caught 4 of 9 AI samples and missed all 3 Claude texts. Both are interested parties. The most common complaint in Pangram's Trustpilot reviews (3.3 from 126 reviews) is human writing flagged as AI, often from students required to use it.

Pangram scores how much of a document looks AI-generated and marks segments as human, AI-assisted or AI-generated, rather than one yes or no. That middle category matters when the real question is whether a human draft was heavily edited by a chatbot. It runs in the web app, Chrome and Firefox extensions, Google Docs and Gmail, and connects to Canvas, Google Classroom, Moodle and Brightspace. Paid scans add similarity (plagiarism-style) checks and an AI image detector.

On its pricing page, read November 3, 2026, Individual is $20 a month for up to 300,000 words and 100 image scans, after a 7-day free trial; annual billing saves $60. Professional is $65 a month with five times the words and image scans, and Team is $40 a month for 2 seats. The pricing page lists no free plan, but the homepage FAQ says a free account gets 20 checks a day. Pangram's homepage claims a false positive rate of 1 in 10,000; PCWorld's review found very few false positives but weaker results on heavily edited and mixed text.

Scribbr AI Detector is free, unlimited and needs no sign-up, up to 1,200 words per check. It returns a 0-100% score plus paragraph labels: AI-generated, AI-generated and AI-refined, human-written and AI-refined, or human-written. It covers English, Spanish, German and French, and Scribbr says it does not store or share submitted text. Its own FAQ says the free version catches older GPT models with average accuracy and that the premium check is better on GPT-4-class text. The premium AI percentage is not sold alone: it comes inside a plagiarism report from $19.95 per document (prices read November 2, 2026). Best for a student checking their own essay before submitting, or a teacher wanting a quick second opinion.

It's AI gives an AI score with a sentence-level Deep AI Scan, PDF certificates, a plagiarism checker on paid plans, a Chrome extension, Canvas LMS and an API. Detection covers English, Arabic, Spanish, French and German. On its pricing page, read November 3, 2026, the free plan has 4,000 words and 3 deep scans; Plus is $9 a month ($7 billed yearly) for 150,000 words; Premium is $15 for 300,000 words; Pro is $25 for 500,000. Schools pay $5 per student per year with 500,000 words a month per teacher. The cards do not say whether allowances reset monthly, and the terms say fees are non-refundable. Its accuracy page reports results on the public RAID benchmark and a 0.8% false positive rate on a student-essay set; these are vendor-reported. Estimated Google search traffic to its-ai.org rose from about 2,000 visits a month in July to about 12,800 in October 2026.

Originality.ai is aimed at web publishers and content teams. On its pricing page, read November 3, 2026, Pro is $14.95 a month, or $12.95 a month billed yearly ($155.40 a year), for 200,000 words (2,000 credits) a month; Enterprise is $179 a month, or $136.58 billed yearly, for 1.5 million words. One credit covers 100 words of AI checking; an AI plus plagiarism check uses two. Monthly credits expire at the end of each month. The free tier is stated two ways on the same page: 10,000 words one time on the plan card, and 3 scans a day in the comparison table.

GPTZero is the largest site in the category by our traffic estimate (about 6.9 million estimated Google search visits in October 2026). Its pricing page did not show prices when we read it on November 3, 2026, so we quote none. It did show a Professional Team plan with 500,000 words per member per month, a minimum of 2 seats and card payment only, with invoicing through sales. Check the price at checkout before you commit.

"Humanizer" tools rewrite AI text so detectors score it lower, and they are a large business: in our traffic study, the fastest-growing site in this whole category was a free humanizer. Detector vendors say they test against them. Pangram's homepage claims it can detect AI text "even after it has been humanized"; we have not verified that. We do not recommend or link humanizers here. For a teacher, the practical point is that a low score does not clear a text any more than a high score convicts it.

• Treat the score as a reason to look closer, never as the finding. Do not base a grade, rejection or misconduct case on a detector alone. The vendors' own terms say it is not proof.
• Scan long passages. Short texts are the least reliable; Pangram will not score under 50 words, and Scribbr recommends longer passages over single paragraphs.
• Read the highlighted sentences, not just the percentage. Sentence and paragraph labels show whether a flag is one pasted section or the whole piece.
• Get a second signal. Run a second detector, and look at evidence a detector cannot see: document version history, drafts and notes, and whether the writing matches the person's earlier work.
• Be careful with non-native English writers. False positives on human writing are the main risk, and detectors rarely publish false positive rates for non-native writing.
• Talk before you accuse. Ask the writer to walk through how they produced the piece. That conversation settles more cases than any score.

• You grade or edit inside Google Docs, Gmail or an LMS: Pangram.
• You want a free check with no account: Scribbr AI Detector, in 1,200-word pieces.
• You want the lowest monthly price, or a school-wide price per student: It's AI.
• You publish content and also need plagiarism checks: Originality.ai.
• Your school already licenses Turnitin or GPTZero: use that report first, and apply the same rules above.

What is the most accurate AI detector?

There is no neutral, current answer. Most accuracy figures are published by the detector vendors themselves, and their tests disagree: Scribbr's own test rated its free tool at 78%, while a Pangram test found the same tool missed all three Claude samples. Pangram reports a 1 in 10,000 false positive rate on its homepage. Treat any accuracy claim as the vendor's.

Can an AI detector prove that a student used ChatGPT?

No. A detector gives a probability that text was machine-written. It's AI's terms say results are not definitive proof, and Scribbr says no detector is fully accurate. Use a score as a reason to look at drafts, version history and to talk to the student, not as the finding.

Is there a free AI detector?

Yes. Scribbr's AI Detector is free and unlimited up to 1,200 words per check with no account. It's AI gives 4,000 free words, Pangram's homepage says a free account gets 20 checks a day, and Originality.ai offers a small free allowance. Prices read November 3, 2026.

What is the cheapest paid AI detector?

Of the plans we checked, It's AI Plus at $9 a month ($7 billed yearly) for 150,000 words is the cheapest. Originality.ai Pro is $14.95 a month for 200,000 words and Pangram Individual is $20 a month for 300,000 words.

Can AI detectors catch humanized text?

Some vendors say so. Pangram's homepage claims it detects AI text after it has been humanized. We have not tested that claim, and no detector publishes independent results on every humanizer, so a low score on its own does not show a text is human-written.

Why do AI detectors flag human writing?

Detectors look for statistical patterns common in model output, and some human writing shares them: short texts, formulaic or templated writing, and plain prose from non-native English writers. False positives are the most common complaint in detector reviews, which is why a score should never be used alone.