--- title: "Is there a tool that detects ai writing?" url: https://isthereathing.com/a-tool-that-detects-ai-writing/ answer: "yes" summary: "Yes, several, and most have a free tier. None of them is proof: even Turnitin says its false positive rate is not zero, so treat any score as a reason to look closer, not a verdict." category: "Writing & AI text" published: 2026-10-02 updated: 2026-10-02 author: "Jack Stovell" publisher: "Adapt Progress Evolve Limited" language: en-GB --- # Is there a tool that detects ai writing? **Answer: yes.** Yes, several, and most have a free tier. None of them is proof: even Turnitin says its false positive rate is not zero, so treat any score as a reason to look closer, not a verdict. (Source: [Turnitin: Understanding false positives within our AI writing detection capabilities](https://www.turnitin.com/blog/understanding-false-positives-within-our-ai-writing-detection-capabilities)) Yes, several tools detect AI writing, and most of them have a free tier. None of them is proof, though: even Turnitin says its false positive rate is not zero, so treat any score as a reason to look closer, not a verdict. ## The shortlist Ours: made by the same studio that runs this site. ### GPTZero AI-text detector for writing and essays, with a Chrome extension. - Link: https://gptzero.me - Free tier: yes. Up to 10,000 words a month, plus the Chrome extension (its own FAQ). - Paid from: €9.99 a month (billed annually), Premium (shown to us in euros on 2026-10-02 (local currency may differ); Premium covers up to 300,000 words a month) - Best at: A free monthly allowance for checking the odd essay or post. - The catch: Prices showed to us in euros, so UK prices may differ; the cheapest paid plan is Premium at €9.99 a month billed annually. - Platforms: web, Chrome extension - Source: [GPTZero pricing page and FAQ](https://gptzero.me/pricing) ### Originality.ai AI and plagiarism checker aimed at publishers and content teams. - Link: https://originality.ai - Free tier: yes. Basic: 3 scans a day, up to 2,000 words a scan, AI detection only. - Paid from: $12.95 a month (billed annually), Pro (USD only on the pricing page; $14.95 a month billed monthly; 1 credit = 100 words, 2,000 credits a month) - Best at: Checking web content at volume, with Chrome, Google Docs and Firefox add-ons. - The catch: The free plan is AI detection only, capped at 3 scans a day. - Platforms: web, Chrome extension, Google Docs add-on, Firefox extension - Source: [Originality.ai pricing](https://originality.ai/pricing) ### Pangram AI-text detector that also checks images, with plagiarism checks on paid plans. - Link: https://www.pangram.com - Free tier: yes. Up to 2,000 words a day and 3 image detection scans a day, no card needed. - Paid from: $20 a month (billed monthly), Individual (USD only on the pricing page; $180 a year billed annually (shown as save $60); 7-day free trial; up to 300,000 words a month; plagiarism checks from Individual) - Best at: Daily free checks, plus image detection on the free plan. - The catch: Paid plans are priced in US dollars: the cheapest is $20 a month billed monthly, or $180 a year billed annually. - Platforms: web, Chrome extension, Google Docs - Source: [Pangram pricing](https://www.pangram.com/pricing) ### ScriptGrain AI-writing check (ours) A free stylometric check: a human-vs-AI confidence score plus which habits read as machine-written. - Link: https://scriptgrain.com/ai-detect - Free tier: yes. The check itself is free with a free account; no card needed. Humanising toward your own voice is paid, from £12 a month. - Paid from: £12 a month, Writer (Only needed for humanise/polish credits; the check is free) - Best at: Showing you why text reads as AI (sentence rhythm, hedging, stock phrases), not just a percentage. - The catch: You need a free account to see results, and it is a style check, so it can flag well-edited or second-language writing. - Platforms: web - Source: [ScriptGrain free AI-writing check](https://scriptgrain.com/ai-detect) ### Turnitin The detector many schools and universities run on submitted work. - Link: https://www.turnitin.com - Free tier: no. No individual free tier. - Paid from: not checked (not applicable: institutional pricing) - Best at: Knowing what your institution's checker is likely to say, if you're a student. - The catch: You can't buy its AI detection as an individual: Turnitin says it is only available through an institutional or organisational subscription. Its own guidance says results under 20% are less reliable and it needs 300+ words. - Platforms: institutional platforms - Source: [Turnitin Help: Do individual submission credits include AI Writing Detection?](https://helpcenter.turnitin.com/hc/en-us/articles/47025932834701-Do-individual-submission-credits-include-AI-Writing-Detection) ## How they compare Which one suits you depends on what you're after: volume, budget, whether you're a student, or whether you want to understand why a bit of text got flagged. Here are five needs, one at a time. ### If you want a monthly free allowance GPTZero offers one. Its free plan covers up to 10,000 words a month, plus a Chrome extension (that's from its own FAQ), which suits checking the odd essay or post. The catch is the pricing. GPTZero showed us prices in euros, so what you'd pay in pounds may differ. The allowance is monthly rather than daily, so if you use it up early in the month, you wait. ### If you want a free check every day, including images That's Pangram. The free plan allows up to 2,000 words a day and 3 image detection scans a day, no card needed, which matters if you're looking at more than text. Paid plans add plagiarism checks. What you give up is a cheap step up: the cheapest paid plan is $20 a month billed monthly, or $180 a year billed annually, and it's priced in US dollars only. ### If you check web content in Docs or Firefox Originality.ai is aimed at publishers and content teams. It has Chrome, Google Docs and Firefox add-ons, and a free Basic plan of 3 scans a day. But the free plan is AI detection only, and each scan tops out at 2,000 words. A long article means splitting it up, and three scans a day won't go far if you check a lot of content. ### If you are a student wondering what your school will see Turnitin is the detector many schools and universities run, so it's the closest thing to knowing what your institution's checker might say. The problem is you can't buy its AI detection as an individual. Turnitin says it's only available through an institutional or organisational subscription, so you're relying on your institution to run it. ### If you want to see why text reads as AI Our own ScriptGrain AI-writing check is aimed at this. Our check shows which habits read as machine-written (sentence rhythm, hedging, stock phrases), plus a human-vs-AI confidence score, not just a percentage. Our check is free, but you need a free account to see results. And because ScriptGrain's check, which is ours, is a style check, it can flag well-edited or second-language writing that a person wrote. Humanising text toward your own voice is the paid part of ScriptGrain, our own product, from £12 a month, and you don't need it for the check. ### When paying is worth it Free tiers cover occasional checks, so paying suits regular volume. GPTZero Premium is €9.99 a month billed annually, for up to 300,000 words a month. Originality.ai Pro is $12.95 a month billed annually, or $14.95 billed monthly, and Pangram's Individual plan is $20 a month billed monthly, or $180 a year billed annually, for up to 300,000 words a month. Paying gets you room, not certainty. A paid score is still not proof. ## What to watch for Even Turnitin says its false positive rate is not zero. So treat a score as a reason to look closer, not a verdict. That goes for every detector here, free or paid. Turnitin also says results under 20% are less reliable, and it needs 300+ words to score a document. Short pieces, like a paragraph or two pasted in, give a detector less to go on. Then there's money. GPTZero showed us euro prices, while Originality.ai and Pangram price in US dollars only, so UK prices may differ. Check the pricing page before you commit. ## How we checked We read each tool's own pricing and help pages on 2 October 2026 and took free allowances and prices from there. We have not yet run the same samples through every detector, so we make no accuracy claims of our own, and the accuracy figures vendors publish are theirs, not ours. Not yet tested: the same three text samples (fully human, fully AI, AI edited by a person) run through every detector, results tabulated. Every detector gets some human writing wrong. Turnitin aims for under 1% false positives on whole documents, says the rate is not zero, and adds that results below 20% AI are less reliable and documents under 300 words aren't scored. ## If none of these fit If the stakes are high, like an accusation over coursework, don't rely on any detector. Ask for the draft history (Google Docs version history or Word's) and talk through the work. That shows how it was written better than a score can. ## Also typed as - is there a website that can detect ai writing - is there a tool that can detect chatgpt - is there a tool to detect ai generated text - is there an app that detects ai ## Related questions - [Is there an app that can humanize ai text?](https://isthereathing.com/an-app-that-can-humanize-ai-text/) - [Is there an ai that can help me write a book?](https://isthereathing.com/an-ai-that-can-help-me-write-a-book/) - [Is there a website that can detect ai images?](https://isthereathing.com/a-website-that-can-detect-ai-images/) ## Sources - [Turnitin: Understanding false positives within our AI writing detection capabilities](https://www.turnitin.com/blog/understanding-false-positives-within-our-ai-writing-detection-capabilities) (checked 2026-10-02) - [GPTZero pricing page and FAQ](https://gptzero.me/pricing) (checked 2026-10-02) - [Originality.ai pricing](https://originality.ai/pricing) (checked 2026-10-02) - [Originality.ai homepage (extensions)](https://www.originality.ai/) (checked 2026-10-02) - [Pangram pricing](https://www.pangram.com/pricing) (checked 2026-10-02) - [Pangram homepage (integrations)](https://www.pangram.com/) (checked 2026-10-02) - [ScriptGrain free AI-writing check](https://scriptgrain.com/ai-detect) (checked 2026-10-02) - [ScriptGrain humanise AI writing](https://scriptgrain.com/humanize-ai-writing) (checked 2026-10-02) - [ScriptGrain pricing](https://scriptgrain.com/pricing) (checked 2026-10-02) - [Turnitin: AI writing detection update from Turnitin's Chief Product Officer](https://www.turnitin.com/blog/ai-writing-detection-update-from-turnitins-chief-product-officer) (checked 2026-10-02) - [Turnitin Help: Do individual submission credits include AI Writing Detection?](https://helpcenter.turnitin.com/hc/en-us/articles/47025932834701-Do-individual-submission-credits-include-AI-Writing-Detection) (checked 2026-10-02) ## Questions people ask ### Can an AI detector prove someone used ChatGPT? No. They give a probability, and even Turnitin says its false positive rate is not zero. Use a score as a reason to look closer. ### Is there a free AI detector? Yes. GPTZero gives 10,000 words a month free, Pangram 2,000 words a day, Originality.ai 3 scans a day, and ScriptGrain's check is free with an account. ### Why was my own writing flagged as AI? Detectors look for patterns like even sentence lengths and stock phrases. Tidy, heavily edited or second-language writing can share those patterns, and short texts give them less to go on. ### Do these work on images too? Some do: Pangram's free plan includes 3 image checks a day. The rest of this list is mainly for text.