- AI-Powered Plagiarism Detection: Scans text against billions of web pages and academic databases.
- Originality Score: Provides a percentage-based view of how unique a document is.
- Citation Suggestions: Recommends proper citations in APA, MLA, or Chicago styles.
- AI & Authorship Transparency: Categorizes text by source, including human-written and AI-generated.
- Integrated Writing Feedback: Combines plagiarism checks with grammar, clarity, and tone improvements.
Grammarly Plagiarism Checker
AI-powered plagiarism detection with writing, citation, and integrity checks
Updated February 27, 2026
Grammarly Plagiarism Checker Overview
Grammarly Plagiarism Checker is an AI-driven tool that scans text against billions of web pages and academic databases to identify unoriginal content. Designed for students, educators, and professionals, it provides originality scores, citation suggestions, and integrated grammar feedback.
The plagiarism checker works seamlessly within Grammarly’s broader writing assistant, helping users maintain academic integrity while improving clarity, tone, and overall writing quality.
Key Features
Pricing
| Plan | Price | Featured |
|---|---|---|
| Free | $0/month | Basic grammar and spelling checks, tone detection, 100 AI prompts/month |
| Pro | $12/month (Billed Annually) / ~$30/month (Billed Monthly) | Plagiarism detection, AI-generated text detection, 2,000 AI prompts/member/month |
| Enterprise | Contact Sales (Custom Pricing) | Unlimited AI prompts, advanced security & BYOK encryption, dedicated support |
Price details: https://www.grammarly.com/plans
Pros
Competitor |
Pros |
|---|---|
| Turnitin | Grammarly is more accessible for individuals, offering a simple interface and affordable Pro pricing. It integrates plagiarism checks directly with grammar and style feedback, reducing the need to switch tools. Unlike Turnitin, it is easy to use outside institutional environments. |
| Copyscape | Compared to Copyscape’s pay-per-scan model, Grammarly provides unlimited checks within a subscription. It also adds grammar, tone, and AI writing support, making it a more comprehensive writing assistant rather than a standalone plagiarism scanner. |
| Quetext | Grammarly offers broader writing support beyond plagiarism, including real-time suggestions and AI detection. Its interface is cleaner and better suited for continuous writing workflows, while Quetext focuses more narrowly on similarity detection. |
| PlagScan | Grammarly is easier for non-academic users and integrates directly into browsers and editors. It provides instant feedback and citation help, whereas PlagScan is more document-based and less intuitive for everyday writing. |
| Originality.ai | Grammarly is more user-friendly for students and professionals, combining plagiarism and grammar tools in one platform. Originality.ai is more technical and SEO-focused, while Grammarly prioritizes clarity, usability, and writing improvement. |
Cons
Competitor |
Cons |
|---|---|
| Turnitin | Grammarly’s plagiarism detection is generally less rigorous than Turnitin’s academic database coverage. Universities often trust Turnitin more for formal submissions, while Grammarly is seen as a pre-check rather than an authoritative academic standard. |
| Copyscape | Copyscape can be more precise for web content duplication, especially for SEO use cases. Grammarly’s plagiarism checker is broader but sometimes flags common phrases, which may require additional manual review. |
| Quetext | Quetext provides clearer similarity breakdowns for matched sources. Grammarly’s reports are simpler and may feel less detailed for users who want granular analysis of overlapping text. |
| PlagScan | PlagScan offers more formal reporting options for institutions. Grammarly’s plagiarism reports are designed for writers, not compliance-heavy academic or legal documentation. |
| Originality.ai | Originality.ai can be stronger for detecting AI-generated content at scale. Grammarly’s AI detection is integrated but may be less specialized for publishers who need strict AI-authorship verification. |
Reviews
- co.uk Review: The tester found Grammarly Plagiarism Checker reliable for “everyday content creation and casual academic work,” especially with its scan across 16 billion web pages and clear source attribution links. It flagged false positives on common phrases and once credited The Verge content to “Syfeed,” which raised concerns about source accuracy.
- Reddit r/Grammarly: Multiple users criticized the AI detector for jumping from 0% to 70–90% on unchanged text and even labeling a piece from 1996 as 38% AI-generated. Grammarly’s AI checker marked entire self-written sections without clearly showing what triggered the score, and one commenter called it “the worst so far” and “very irresponsible.”
- aidetectplus.com Review: The reviewer praised the simple layout that “you don’t get lost clicking around” and liked that no technical skills are required to use it. Grammarly Plagiarism Checker earned credit for readability and fact-checking support, though the article promises “3 Pros, 5 Cons” and highlights that buyers should review pricing and limitations carefully.
- originality.ai Review: Testing at 5% and 15% thresholds showed weaker detection rates for paraphrase plagiarism, with results like 3.0% at the 15% threshold compared to higher scores from competitors. The quick review scored Performance at 6/10 and summarized that the plagiarism checker “isn’t quite as effective as some of the market-leaders,” even though ease of use reached 8/10.
- gptzero.me Review: One long-time user stated bluntly that “Grammarly’s AI and plagiarism checker is not accurate” and described detection scores shifting from 0% to 35% to 90% on the exact same 2,300-word story. The lack of clarity about which passages triggered AI flags left students and teachers without enough evidence to challenge or understand the results.
