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Learn moreAI Plagiarism Checker
AI detection that flags sentences, not just whole documents
Beginner API
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What is AI Plagiarism Checker?
AI Plagiarism Checker is an AI checker tool. A sentence-level AI detector from plagiarismcheck.org that highlights lines with machine-writing traits instead of returning one document score. It ships with an adjustable sensitivity threshold, published false-positive data, plagiarism checking in the same report, LMS integration and multilingual support for English and Spanish content.
AI Plagiarism Checker, the AI detection product from plagiarismcheck.org, works differently from tools that return a single percentage for a whole document. Its classifier evaluates the text sentence by sentence, assigns each line a probability score between 0 and 100, and highlights the passages that carry machine writing traits. The report is meant as evidence rather than a verdict: a reviewer sees which paragraphs triggered the detector and decides whether that volume of flagged text matters for the job at hand. Under the hood the detector combines perplexity and burstiness measurements with a natural language processing pipeline trained on paired human and machine text. That classifier weighs vocabulary, sentence structure, punctuation and transition phrasing typical of specific model families. The vendor reports 99.23 percent sentence-level accuracy across the seven most recent models tested, and it states its own false-positive rate openly: 1.04 percent of sentences in 2,805 human-written documents were incorrectly flagged, with the document-level figure falling to zero at the default settings. The practical draw is the adjustable threshold. Editing a social post and reviewing a thesis are not the same task, so users drag a slider to set how many flagged sentences justify a review. Published test data on 3,514 documents shows that flagging documents above 24 percent flagged sentences catches 100 percent of AI documents while mislabeling roughly 1 in 255 human ones. The detector also sits inside a broader checker, so AI results, plagiarism matching, an originality score and authorship verification can appear in one report. Educators are the core audience, and the tool supports them with LMS connections, a Google Docs add-on and browser extensions, plus a policy of not retaining submitted documents by default. SEO and content teams use it as a pre-publication filter, and newsrooms, HR and legal reviewers apply it to reports, resumes and articles. It competes with Turnitin and standalone AI detectors by offering line-level transparency and configurable sensitivity instead of a single opaque number.
How do you use AI Plagiarism Checker?
1Open the detector and paste or upload text
Go to the AI detector page and either paste your text into the input box or drag in a file. The page states a 100-word minimum, with best accuracy between 200 and 550 words; doc, docx, txt, rtf, pdf and presentation formats are accepted.2Run the sentence-level scan
Start the check and wait for the tool to classify each sentence individually, assigning probability scores and marking the lines that match AI writing patterns.3Read the flagged lines rather than the headline number
Work through the highlighted sentences and judge whether the flagged material is a genuine concern for your use case. The report is designed to show evidence, so context and your own expertise decide the outcome.4Adjust the threshold for the task
Move the sensitivity slider to set how many flagged sentences should mark a document for review. A light check for a social post and a strict check for academic work call for different settings.5Review the accuracy evidence before relying on results
Read the published method and competitor comparison to understand how accuracy and false-positive rates were measured across models and document types.6Check originality alongside AI traces
Use the integrated plagiarism checker so matching extracts and sources appear in the same report, giving a fuller picture of whether the text is original and human-authored.
Pros and cons
Pros
- Highlights specific sentences with AI traits, so reviewers see the evidence behind a score instead of an unexplained percentageAI
- Publishes measured error rates and a threshold slider that lets users trade AI catch rate against false positivesAI
- Combines AI detection with plagiarism matching, an originality score and authorship verification in one reportAI
- Connects to Moodle, Canvas, Google Classroom, Brightspace, Schoology, Blackboard and Populi, plus an API and Google Docs add-onAI
- Documents are not retained by default, and educators can manage their own repository within LMS integrationsAI
Cons
- AI detection is offered for English and Spanish only, even though similarity checks cover 15 languagesAI
- The vendor concedes accuracy drops on humanized, hybrid or stealth AI writing, so a clean report is not proof of human authorshipAI
- Sentence-level scores can be misread as conclusive, and no built-in workflow forces reviewers to weigh context before actingAI
- Interface, pricing and account details are not visible on the detector page, so buyers must check the main site before committingAI
- False positives still occur at sentence level (about 1 percent in testing), which matters in high-stakes academic or legal disputesAI
How much does AI Plagiarism Checker cost?
Integrations
LMS connectors for Moodle, Canvas, Google Classroom, Brightspace, Populi, Schoology and Blackboard, an API, browser extensions and a Google Docs add-on.
Learn moreFeatures
Sentence-by-sentence AI classification with per-line probability scores, perplexity and burstiness analysis, an NLP pipeline tuned for predictive text patterns, and coverage of OpenAI, Google, Anthropic and xAI models. Users set their own flagged-sentence threshold, and results can be paired with plagiarism matching, an originality score and authorship verification in a single report.
Learn moreFrequently asked questions about AI Plagiarism Checker
Does AI Plagiarism Checker offer a free trial?
The homepage invites users to try the detector for free before deciding, with no card details or trial length stated on the page.Does AI Plagiarism Checker have an API?
Yes, AI Plagiarism Checker offers an API.How do you use AI Plagiarism Checker?
The walkthrough on this page covers 6 steps: 1. Open the detector and paste or upload text 2. Run the sentence-level scan 3. Read the flagged lines rather than the headline number 4. Adjust the threshold for the task 5. Review the accuracy evidence before relying on results 6. Check originality alongside AI traces.What platforms does AI Plagiarism Checker support?
AI Plagiarism Checker is available on Web App and Browser extension.What does AI Plagiarism Checker integrate with?
LMS connectors for Moodle, Canvas, Google Classroom, Brightspace, Populi, Schoology and Blackboard, an API, browser extensions and a Google Docs add-on.What are the limitations of AI Plagiarism Checker?
AI detection is offered for English and Spanish only, even though similarity checks cover 15 languages. The vendor concedes accuracy drops on humanized, hybrid or stealth AI writing, so a clean report is not proof of human authorship. Sentence-level scores can be misread as conclusive, and no built-in workflow forces reviewers to weigh context before acting.
Status
StatusActive
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Added10/21/2026
Platforms
Web AppBrowser extension
Pricing
FreemiumFree Trial
