Software advice
Best AI Plagiarism Checkers in 2026
An AI plagiarism checker is a web or desktop service that compares a document against web pages, publications and stored submissions to report matching passages, and that also estimates whether the text was written by an AI model. It is not a writing assistant, and its AI score is a probability that a reviewer has to interpret, not proof of authorship.
Quick answer
Plagramme ranks first for printed credit prices, AI detection on every plan and EU storage. Originality.ai fits publishers who scan in volume through an API, and Scribbr fits a student who checks one thesis and pays per document.
Anyone who submits or reviews written work now faces two questions in one scan: did the words come from somewhere else, and did a model write them. Vendors sell both answers under one price, and the pricing models differ more than the detection claims: credits per word, tokens per 18,000 characters, per-check fees, one-time packages and institutional quotes. This ranking weighs what is printed about price, how AI detection is packaged, where documents go and whether the vendor trains models on them. We read vendor pages in November 2026 and ran no checks, so no accuracy figure is claimed here.
The 13 best AI plagiarism checkers in 2026, ranked
There is no score. Vendors can pay for more visibility on this website, for example a higher place in a ranking or more room on a page. Commercial relationships can also affect which products we feature and how prominently. How we rank.
| # | Tool | Best for | Free plan | Entry price |
|---|---|---|---|---|
| 1 | Plagramme | Writers and small teams that want EU-stored documents and AI detection on every plan | No | USD 14.95 per month (Basic) |
| 2 | Originality.ai | Publishers and content teams that scan many articles and want API, extensions and bulk scans | Trial | $12.95 per month billed yearly |
| 3 | Copyleaks | Multilingual teams and schools that need AI detection beyond English plus an API and LMS connection | Trial | $13.99 per month billed annually |
| 4 | Quetext | Students and solo writers who want a free tier, browser extensions and a monthly word allowance | Yes | $14.99 per month (Essential) |
| 5 | PlagiarismSearch | Occasional checkers who want a pay-once package that bundles plagiarism and AI submissions | No | $9.95 one-time (Light package) |
| 6 | Scribbr | Students who check one thesis or paper and want a similarity percentage plus an AI detector | Yes | $19.95 per check (up to 7,499 words) |
| 7 | PlagAware | German-speaking freelancers, schools and publishers who want prepaid credits and German hosting | Yes | From €12.99 for 100 pages |
| 8 | Compilatio | French and European schools that want LMS connections and data hosted in Europe | Trial | Quoted |
| 9 | StrikePlagiarism | Universities that want per-document pricing and an AI module inside the similarity report | No | 2.33 EUR per token (18,000 characters) |
| 10 | Plagiarism Checker X | Windows users who prefer a desktop app and a one-time licence over a subscription | Yes | $14 per month (Personal) |
| 11 | Grammarly | Writers who already use Grammarly for editing and want occasional plagiarism and AI checks on Pro | Yes | €12 on Pro, billing basis not captured |
| 12 | Turnitin | Universities that already run Turnitin Originality and want AI detection added to that licence | No | Quoted |
| 13 | Viper | Students who want browser-based pay-as-you-go credits with no subscription and no software install | Trial | £5.00 for 10 credits |
- 1
Plagramme takes first place because AI detection is not an upsell: every plan spends one credit per word on it, and the price list runs from USD 14.95 to an unlimited tier. The privacy policy says data is stored and processed in the EU or EEA by default, which few rivals state. No API or integrations are named, so it suits manual checks, not pipelines.
Strong on
- Privacy policy names EU/EEA storage and processing as the default
- AI detection and cross-language plagiarism checks cost the same single credit per word
- Three published tiers, from 10,000 credits a month to unlimited
Weak on
- No API and no platform integrations named on the pages read
- Annual prices and the middle plan's name were not captured, only monthly amounts
Skip it if: Teams that need to push documents from an LMS or a CMS into a checker automatically. Credits are spent at one per word for plagiarism, AI detection and cross-language checks. Annual amounts were not captured.
- 2
Originality.ai ranks second because credit math is easy: 100 words per credit, 200K words on a $12.95 Pro plan, and 1.5M words on Enterprise with an API. It loses the top spot on data terms, since scan history may train models unless the customer opts out, and the pages read name no hosting region or certification.
Strong on
- Prints word allowances for every tier, including a $8.62 extra seat on yearly Pro billing
- Plagiarism and AI checks share one credit pool
- Chrome and Google Docs extensions, a Moodle plugin and an MCP server
Weak on
- Scan results may be used for model training unless the customer opts out
- Pro scan history lasts 30 days, and one year needs Enterprise
Skip it if: Buyers who need written assurance that submitted text never trains a model. Pro includes 200K words a month. Monthly billing costs $14.95. Free is a single 10K-word allowance.
- 3
Copyleaks sits third because it covers the widest ground: AI detection in 30-plus languages, plagiarism in 100-plus, and AI image detection in the same report. Pro adds 25 seats and sitemap scans. The terms say the company may train models on submitted information, with an opt-out by request, and its headquarters is not stated on the pages read.
Strong on
- AI text detection in 30-plus languages and plagiarism detection in 100-plus
- Pro adds website sitemap scans and cross-language translation detection
- Browser extension, Google Docs add-on, WordPress and LMS integrations
Weak on
- Training on customer data is allowed unless direct customers contact support to opt out
- Seats beyond the 25 in Pro are bought separately
Skip it if: Buyers whose policy forbids vendors from using uploaded text to improve detection models. Personal costs $16.99 on monthly billing. Pro starts at $74.99 a month billed annually. Enterprise is quote-only.
- 4
Quetext ranks fourth. It offers a real free tier (1,000 words per check), a 100k-word Essential plan and an MCP server, and the AI detector is part of every plan. The privacy policy makes user content eligible for AI training by default, and opting out means emailing privacy@quetext.com, which is a step down from a settings toggle.
Strong on
- Free plan includes both the plagiarism checker and the AI Content Detector
- Essential adds 20 bulk files and API access
- Chrome, Firefox and Edge extensions plus a Google Docs add-on
Weak on
- AI training use is the default and opt-out is by email
- No company address was found on the privacy or terms pages
Skip it if: Teams that need a clear legal entity address and a self-service training opt-out. Free covers 1,000 words per tool. Essential allows 100k words a month. Professional starts at $29.98 a month.
- 5
PlagiarismSearch ranks fifth for its cheapest entry point: $9.95 buys one plagiarism and one AI submission with no time limit, and 50 of each costs $41.95. Premium monthly adds an API and storage. The policy says customer content may sit on US infrastructure with some processing in Europe, and no certification or training statement appears.
Strong on
- One-time packages carry no expiry, so light users pay only when they check
- Premium monthly includes API access, storage and 300 AI submissions
- Viber and Telegram chat bot for quick checks
Weak on
- Monthly Light has no AI submissions listed, only 100 plagiarism checks
- Reports move to an archive after about 30 days with fewer editing functions
Skip it if: Buyers who need a stated hosting region inside the EU or a certification. One-time packages never expire. Monthly packages recur. The prices page shows a dollar sign without naming the currency.
- 6
Scribbr ranks sixth. Pay-per-check pricing ($19.95, $29.95 and $39.95 by length) suits one-off theses, and a premium check includes the AI Detector and AI Proofreader free. It is a poor fit for frequent checkers because every document is bought separately, and the pages read give no API, hosting region or training statement, which keeps it below the tools with clearer data terms.
Strong on
- Premium report includes the AI Detector and a self-plagiarism check against earlier uploads
- Orders are deleted automatically from the server after 12 months
- Word and PDF upload plus Google Drive import for documents
Weak on
- Every premium check is bought one at a time, with no subscription
- The free report needs 300 words and hides the source details
Skip it if: Anyone who checks many documents a month or needs an API. Priced per document size, not as a subscription. A free report flags risk but hides the sources.
- 7
PlagAware takes seventh place on data handling, not detection: documents are hosted by Hetzner in Gunzenhausen, Germany, and deleting an account deletes the application data. The AI detector has its own page, but the pages read do not describe how it works or what it costs, so the AI claim is the least documented in this top half.
Strong on
- Hosting by Hetzner in Germany is named on the data protection page
- Prepaid credits need no contract, subscription or minimum spend
- Text monitoring watches your published pages for copies of your text
Weak on
- The AI detector method and its pricing are not described on the pages read
- Monthly subscription prices were not captured from the menu
Skip it if: Buyers who choose a checker mainly for its AI detection and need documented accuracy claims. Prepaid ScanCredits cost one per page. A free account covers 10 pages. Volume licences start at €79 a year.
- 8
Compilatio ranks eighth because buyers cannot see a price. Magister covers plagiarism and AI detection for teachers and connects to Blackboard, Brightspace, Canvas, Moodle and Microsoft Teams, and the GDPR page says data stays in Europe. A quote is the only route for institutions, and the free student account is a taste of the report, not a working plan.
Strong on
- Data hosting in Europe with ISO 9001 and AGID named on its GDPR page
- LMS connections for five named platforms, plus API and SSO
- Free first analysis for students through the Studium account
Weak on
- No published price for Magister, so budget comparison needs a demo
- Retention period was not stated on the pages read
Skip it if: Individual writers or freelancers who need a price list and a pay-as-you-go option. Prices are not published. Students get a free account and a free first analysis. Magister needs a demo.
- 9
StrikePlagiarism ranks ninth. It builds an AI probability and an AI Content Indicator into the similarity report, and it publishes both token prices and corporate price bands, which most institutional vendors keep private. Tokens expire in six months, individuals have no free tier, and the pages read give no hosting region, document retention period or training statement.
Strong on
- AI Content Detection module sits inside the Similarity Report
- Corporate price bands are published as estimates, from 0.03 to 0.10 per page
- API, LTI and LMS integrations are listed on the site
Weak on
- Unused Tokens expire after six months, with no refund noted
- Individuals have no free plan and must pay before each check
Skip it if: Occasional users who dislike prepaid tokens that lapse after six months. Tokens expire after six months. Corporate prices are estimates per account, document or page, quoted by sales.
- 10
Plagiarism Checker X ranks tenth. It is the only entry with a Windows desktop app and a pay-once licence at $39.95, and paid plans count AI words in the same allowance as plagiarism words. The privacy pages state GDPR compliance but give no retention, region or training information, and no public API was seen on the pages read.
Strong on
- One-time Professional licence includes a one-year maintenance plan
- Side-by-side comparison of two texts and bulk upload on paid plans
- Monthly Business plan includes 10 team seats and logo on reports
Weak on
- Updates on one-time licences stop after 365 days without the maintenance plan
- Retention and hosting region are not stated anywhere
Skip it if: Mac users, teams that need an API, and buyers who need a stated data region. Basic is free with 20 searches a day. A one-time Professional licence costs $39.95 with one year of updates.
- 11
Grammarly ranks eleventh as a checker because detection is a side feature of a writing assistant: it arrives on Pro (€12) next to rewrites and 2,000 AI prompts, with no word allowance printed. The privacy policy lets users decide whether content trains AI models. Teams buying only for detection get less reporting depth than from the dedicated tools above.
Strong on
- Plagiarism and AI text detection sit beside grammar, tone and rewrite tools
- Account settings include controls over whether your content trains AI models
- Enterprise adds BYOK encryption and data loss prevention
Weak on
- Detection is absent from the Free plan and only starts on Pro
- Pro billing basis and detection allowances were not captured
Skip it if: Institutions and publishers that need bulk scans or an API for checking. Free has no plagiarism or AI detection. Pro adds both. Enterprise is quoted by sales.
- 12
Turnitin ranks twelfth because the buyer cannot be an individual and cannot see a price. The trust center is the clearest data statement in the group: no generative model is trained on customer data, and the AI classifier is the only thing that may learn from writing. Clarity feedback can differ between classes, since each instructor can switch it on or off.
Strong on
- Trust center says no generative AI or LLM is trained on customer data
- AI detection classifier ships inside the Originality licence
- iThenticate AI covers research integrity use as a separate product
Weak on
- Submitted writing may train the AI detection classifier when Originality with AI detection is on
- Few integrations were named on the pages read, only sister products
Skip it if: Individual students, freelancers or small publishers who want a price list and instant signup. Institutional products only. The pages read publish no prices, and sales provides quotes.
- 13
Viper closes the list. Credit bundles from £5.00 to £69.95 make costs easy to predict, and the browser app needs no install. The weak points are documentation: AI detection is named only on the About page, no hosting region, retention or training statement appears, and its privacy policy warns free scans should not contain personal data.
Strong on
- Credits start at £5.00 and fall to £0.14 per 250 words in the largest bundle
- Runs in any standard browser, with a credit calculator
- Free scanning service is mentioned in the privacy policy
Weak on
- AI detection is mentioned briefly on the About page, with no description of how it works
- Prices are shown in pounds only, with no other currency listed
Skip it if: Buyers who need written data handling terms, an API or an EU hosting statement. One credit covers 250 words. Bundles run to £69.95 for 500 credits, priced in pounds only.
How these AI plagiarism checkers were judged
How reliable is AI detection inside a plagiarism checker?
No page we read published an accuracy rate we could verify, so reliability is a judgment about packaging, not a measurement. Turnitin calls its detector a classifier and lets instructors disable Clarity feedback, while StrikePlagiarism returns an AI probability plus an AI Content Indicator inside the similarity report. Copyleaks lists AI detection in 30-plus languages and Quetext in 25. Treat any AI score as a prompt for a human conversation, since detectors can flag legitimate writing. Plagiarism matching itself depends on the source databases, which Compilatio, Scribbr and PlagiarismSearch describe only in general terms.
What does an AI plagiarism check really cost?
Cost depends on how you buy. Scribbr charges $19.95 to $39.95 per document, Viper starts at £5.00 for 10 credits of 250 words, and StrikePlagiarism sells tokens at 2.33 EUR for 18,000 characters. Subscriptions run from $12.95 on Originality.ai Pro to $14.99 on Quetext Essential, with Plagramme at USD 14.95 and Copyleaks at $13.99 on annual billing. PlagiarismSearch is the cheapest single entry at $9.95. Turnitin and Compilatio publish nothing, so an institution must ask for a quote before comparing them.
Does an AI plagiarism checker keep your document or train on it?
Practices split sharply. Turnitin's trust center says no generative model trains on customer data, though its detection classifier may learn from writing when AI detection is enabled. Originality.ai and Copyleaks may use submissions to improve models unless the customer opts out, and Quetext makes opt-out an email request. Plagramme names EU or EEA storage, PlagAware names Hetzner in Germany and Compilatio names European hosting. Scribbr deletes orders after 12 months. Several others state nothing, so ask about retention and training in writing before uploading unpublished work.
How hard is it to leave an AI plagiarism checker?
Lock-in is mild for individuals and heavier for institutions. Per-check and prepaid tools leave nothing behind but past reports, and Scribbr's 12-month deletion and PlagiarismSearch's archive after about 30 days both limit how long reports stay available. Subscriptions such as Originality.ai cap scan history at 30 days on Pro. Institutions face more: LMS connections at Compilatio and StrikePlagiarism, instructor settings at Turnitin and stored submission databases mean that switching vendors changes how similarity history is matched. Export reports to PDF before you cancel.
Which AI plagiarism checker fits a student, a publisher or a university?
Students checking a single thesis do well with Scribbr or Viper, because they pay once and need no integration. Publishers and agencies that scan many articles should look at Originality.ai, Copyleaks or Quetext for API access, extensions and bulk files. Universities should shortlist Turnitin, Compilatio or StrikePlagiarism for LMS connections and instructor controls, and ask each for a price. Windows users who want to avoid subscriptions can consider Plagiarism Checker X. Anyone with a European residency rule should start with Plagramme, PlagAware or Compilatio.
How to choose an AI plagiarism checker in three steps
- Test the checker on text you know the origin of. Paste three samples into every trial: a paragraph you wrote yourself, a paragraph you copied from a published page and a paragraph an AI model drafted for you. Note whether the plagiarism match finds the copied source, whether the AI score flags the model text and, importantly, whether it wrongly flags your own writing. A tool that marks honest work as machine-written creates arguments you will have to settle by hand. Do this before paying, since the free tiers at Quetext and Originality.ai allow small samples.
- Calculate the monthly word count before choosing a pricing model. Add up the words you check each month and compare models. Credits per word at Plagramme or Originality.ai suit steady volume, tokens at StrikePlagiarism and per-check fees at Scribbr suit rare use, and PlagiarismSearch packages sit in between. A 5,000-word thesis checked twice costs very different amounts across the three models, so run the sums for your own volume. Also check whether plagiarism and AI checks draw from one allowance, as they do at Quetext and Plagiarism Checker X, or are counted separately.
- Ask each vendor where documents are stored and whether they train on them. Send one email to every shortlisted vendor asking for the hosting region, the retention period and whether uploaded text feeds model training or a shared database. Copyleaks runs a Shared Data Hub of user-submitted documents, and Turnitin separates its classifier from generative models, so the answers differ in kind, not just in wording. Keep the replies with your purchase record so a later audit can find them. If you handle student work or unpublished manuscripts, make a written answer a condition of paying.
Frequently asked questions
What is the best AI plagiarism checker in 2026?
Plagramme ranks first here because it prints USD 14.95 to USD 299.95 monthly plans, spends one credit per word on AI detection and names EU or EEA storage. Originality.ai is the pick for publishers who scan in volume through an API, and Scribbr suits a student who checks one thesis and pays per document.
Can an AI plagiarism checker prove that a person used ChatGPT?
No. The vendors we read describe AI detection as a probability or classifier output, and none published an accuracy rate we could verify. Turnitin lets instructors switch some AI features off, and StrikePlagiarism shows an AI probability next to an indicator. Use the score to start a conversation, ask for drafts or version history, and avoid disciplinary decisions based on a score alone.
Is there a free AI plagiarism checker?
Yes, with small limits. Quetext Free allows 1,000 words for both the plagiarism checker and the AI Content Detector, Originality.ai gives a one-time 10K words, and Plagiarism Checker X Basic allows 20 searches a day. PlagAware's free account covers 10 pages. Grammarly Free has no plagiarism or AI detection, which starts on Pro. Free tiers suit testing, not a full thesis.
Which AI plagiarism checkers state EU data storage?
Plagramme states storage and processing in the EU or EEA by default, PlagAware names Hetzner in Gunzenhausen, Germany, and Compilatio says data is hosted in Europe. Most others, including Scribbr, Viper, Originality.ai and Copyleaks, did not state a region on the pages we read. Ask the vendor if residency matters, since policy pages can omit it.
Do AI plagiarism checkers train on the documents you upload?
Some may. Originality.ai says scan history and results may help train models unless the customer opts out, Copyleaks says it may use submitted information and offers opt-out through support, and Quetext includes content by default with an email opt-out. Turnitin says no generative model trains on customer data. Several vendors, including Plagramme and Scribbr, did not state a training policy on the pages we read.
How much does it cost to check one thesis for plagiarism and AI text?
Scribbr charges $19.95 for up to 7,499 words and $29.95 for 7,500 to 49,999 words, with the AI Detector included on a premium check. StrikePlagiarism tokens cover 18,000 characters each at 2.33 EUR. Viper's credits cover 250 words each from £5.00 per 10. PlagiarismSearch's $9.95 Light package covers one plagiarism and one AI submission.
Are Turnitin and Compilatio available to individual students?
Mostly not. Turnitin sells institutional licences by quote, and Compilatio's Magister needs a demo request. Compilatio does offer Studium, a free student account with a free first analysis that shows the three main similarity sources. Students without an institution licence usually pick a pay-per-check tool such as Scribbr, Viper or PlagAware prepaid credits.
What should a publisher look for in an AI plagiarism checker?
Look for an API, bulk scanning and a credit allowance that fits monthly volume. Originality.ai offers 200K words on Pro and 1.5M on Enterprise with an API, Copyleaks Pro adds sitemap scans and 25 seats, and Quetext Essential adds 20 bulk files with API access. Check the training opt-out before you send client drafts.