Best AI Detector (2026): 7 Picks, Limits Spelled Out

Originality.ai is built around publishing workflows. The vendor's WordPress plugin page says it can scan a single post or an entire site, and a Chrome extension runs inside Google Docs and can scan a web page or selected text. The extension also offers a replay of how a document was written, which gives an editor context beyond a single score.

The company states a 99%+ accuracy figure and a false positive rate under 1% on its own pages, and also says its scores reflect probability, not guilt. We treat both as vendor claims, because we found no independent audit of those numbers in this research. Credits are word-based, with the plugin page saying 1 credit equals 100 words (a help article says scans that check both AI and plagiarism use more), and a limited free scan tool exists for a quick look.

Pricing pages for this product show different plan figures, some of them from older pages, so we are not printing a number. Check the current price on the vendor page.

Skip it if you only need an occasional free check of a short text, since the paid setup is aimed at teams that scan regularly.

GPTZero is the easiest place to begin because the vendor describes a free plan that needs no credit card and covers up to 10,000 words per month. That is enough to check an essay or a handful of articles, and the plan includes multilingual detection and writing feedback according to GPTZero's own pages.

For independent context, Pangram's write-up of third-party evaluations includes GPTZero in its comparisons. That source is a competitor's summary, so treat it as a pointer to the original studies rather than a verdict. GPTZero's own pages describe paid tiers with higher monthly word limits, but the figures varied between pages we found.

Because the free tier is real, GPTZero is a sensible baseline to compare any other detector against.

Skip it if you need to scan hundreds of thousands of words every month without checking plan limits first.

Copyleaks documents its language coverage more openly than most competitors. The API reference lists 30 languages for AI detection, including Spanish, Japanese, Arabic and Hindi, and says the AI Logic explanation feature covers six of them: English, Spanish, French, Portuguese, German and Italian. That level of detail helps a team decide whether a non-English workflow is realistic.

The vendor's marketing page says the free web tool accepts up to 25,000 characters per scan without an account and flags mixed human and AI text, though its FAQ ties that limit to the browser extension, so confirm the limit. Paid plans are credit-based, with one credit covering up to 250 words or one image, and the vendor sends education and enterprise buyers to sales for custom pricing. The company reports 99%+ accuracy, and a vendor page notes that the number comes from internal testing on English datasets.

Our reading is that Copyleaks fits teams that mix languages or want to wire detection into their own software.

Skip it if you work only in English and want one plain price with no credit math.

Winston AI's pricing is a credit system, and the vendor's help center spells out the burn rate: the AI detector costs 1 credit per word, plagiarism checking costs 2 credits per word, and writing feedback, the fact checker and the essay grader are each 1 credit per word. At those rates, the free plan's 2,000 credits cover roughly 2,000 words of detection, which is enough for a trial but not a routine.

The paid tiers list 100,000, 200,000 and 500,000 credits per month, and the help center says not all features are on every plan. Plagiarism checking, for example, is not on the Essential AI plan. Only Elite users can purchase additional credits mid-cycle, so lower tiers wait for the next billing period.

Winston also publishes comparison pages against GPTZero and Originality.ai, which are marketing material, not independent tests.

Skip it if you check long documents often and want to avoid doing credit arithmetic.

Pangram's selling point is evidence. Its own site advertises 99.98% accuracy and a false positive rate of about 1 in 10,000, which are vendor claims. More useful are the third-party studies it lists: academic comparisons of several detectors, including one where Pangram reports 97.5% detection of fully AI-written and 95% of humanized papers.

Pangram's pages summarize those studies, so a careful buyer should open the original papers before relying on the percentages. Vendor marketing figures and independent figures rarely match, which is worth keeping in mind for any tool in this list.

Plan information is inconsistent across the pages we found: one lists an individual plan at 300,000 words per month, another a plan by scan count, and free scan allowances range from 3 to 20 per day depending on the page. Check the live pricing page before you decide.

Skip it if you need a single, clearly published free allowance.

QuillBot's detector is a convenient extra for people who already use the company's writing tools. The free version takes up to 1,200 words per scan without registration, and the vendor says Premium removes that cap. Its page advises at least 80 words of text for better accuracy, which is a reminder that very short samples are unreliable in every tool.

Language support is described inconsistently: a recent page says 20+ languages, while an older blog post lists six, so confirm your language before relying on it. We found no independent study measuring this detector, so its accuracy is unproven in this research.

For detection alone, the free scan works as a quick second opinion beside GPTZero.

Skip it if you need audited accuracy numbers or long-document scanning without a subscription.

Grammarly takes two routes. Its free AI detector reads finished text, splits it into sections and gives an overall percentage. Its Authorship feature, in contrast, tracks the writing as it happens in Google Docs and Microsoft Word, and uses clipboard information to label pasted text as coming from a generative AI tool, a website or an unknown source, according to Grammarly's help center.

That second route suits people who expect to be asked to prove their process rather than argue with a percentage. Grammarly itself says no AI detector is 100% accurate and recommends pairing detection with Authorship and plagiarism checks. Basic Authorship tracking is available to all users, while detailed attribution and in-report AI detection are on paid plans.

Because Authorship works only in the editors it supports, text drafted elsewhere has no record to show.

Skip it if you write in apps that Grammarly does not cover.

Turnitin is the detector many students meet through their school, not one a freelancer subscribes to. Its published method splits a paper into overlapping segments of a few hundred words, scores each sentence between 0 and 1 for likelihood of AI origin, and averages those scores into a document-level estimate.

The company is more open about error rates than most. It reports a document false positive rate under 1% for papers with 20% or more flagged text, and a sentence-level false positive rate of around 4%. It adds that results below 20% are less reliable, so the report shows an asterisk instead of a score. Turnitin states that it does not make a misconduct finding from the detector, and says its testing found no statistically significant bias against English language learners, which independent researchers have disputed.

These are the vendor's numbers, and we found no independent audit of them in this research.

Skip it if you are an individual buyer, since access normally comes through an institution.