Evaluating the Best Free Plagiarism Checkers: A Comprehensive Analysis
To determine the most effective free plagiarism checkers, we conducted an extensive review of popular tools, addressing key questions such as, “How accurately do they detect plagiarism?” and “Are they genuinely free?”
Research Methodology
Our evaluation involved testing plagiarism detection tools using four distinct test documents, each varying in the level of editing applied.
These test documents contained plagiarized content sourced from 140 references, including Wikipedia articles, news reports, open-access journal publications, websites, theses, dissertations, and PDFs. This structured approach enabled us to assess:
-
The accuracy and reliability of each plagiarism checker, even when texts were modified to different extents.
-
The comprehensiveness of each tool’s database—whether it includes only websites or also incorporates academic journal articles and other sources.
Key Findings: Free vs. Paid Plagiarism Checkers
Our research revealed that many free plagiarism checkers often employ misleading advertising and fall short in several critical aspects compared to their paid counterparts. Based on our analysis, we arrived at the following conclusions:
Plagiarism Checker Comparison
| Plagiarism Checker | Free Plan | Accuracy (%) | Max Free Words | Privacy & Support |
|---|---|---|---|---|
| Grammarly | No (Only plagiarism alert) | <40% | N/A | Documents not stored, no live support |
| PlagAware | One-time 10-page trial | 57% | 10 pages | Documents can be deleted, phone support |
| Scribbr | Limited free check | 88% | No word limit (paid for full report) | Files deleted after 30 days, live support |
| DupliChecker | Yes | 40% | 1,000 words | No document storage, contact form only |
| Prepostseo | Yes | ~40% | 1,000 words | No document storage, no live support |
| Copyleaks | One-time 2,500-word trial | 38% | 2,500 words | Manual file deletion, live chat support |
| Check-Plagiarism | Yes | 37% | 1,000 words | No document storage, limited support |
| Plagiarism Detector | Yes | 35% | 1,000 words | No document storage, no live support |
| Small SEO Tools | Yes | 44% | 1,000 words | No document storage, no dedicated support |
| Quetext | Free 500-word check | 48% | 500 words | No document storage, no live support |
1. Grammarly
Free Plan Availability
Grammarly’s plagiarism checker is not included in its free plan. The free version only indicates the presence of Free plagiarism without revealing specific details, such as the plagiarized sections, percentage of duplication, or original sources.
To access these insights, users must subscribe to Grammarly Premium, which costs $12 per month. Even with a subscription, documents are subject to a 100,000-character limit (approximately 20,000 words).
Accuracy of Plagiarism Detection
Grammarly identified a relatively low percentage of plagiarism, with detection rates falling below 40%, even for unedited texts. Additionally, when plagiarism was detected, it was often partial rather than a full match.
Pros
- Includes a language and citation assistant
- Does not sell or share documents with third parties
Cons
- The free plagiarism report provides minimal information
- Detects a relatively low percentage of plagiarism
- Uses the same color for different sources, making it difficult to differentiate
Usability
As a premium service, Grammarly offers a more polished and user-friendly interface compared to most free plagiarism checkers. It maintains the document’s original formatting to a large extent. However, the tool assigns the same color to all detected sources, making it difficult to distinguish between them. Furthermore, users must divide longer texts into smaller sections for scanning, as the tool has a length restriction.
Premium subscribers also gain access to Grammarly’s language enhancement features and citation assistant.
Trustworthiness
Grammarly maintains user privacy by ensuring that documents are not stored, sold, or shared with third parties.
The platform offers a support page with tutorials, FAQs, and usage tips. While users can submit inquiries via an online form, Grammarly does not provide live customer support.
2. PlagAware
Free Trial and Pricing
PlagAware offers a one-time trial of 10 credits, allowing users to scan up to 10 pages. However, accessing the results requires account registration.
For additional scans, users must purchase credits, starting at 100 credits for $15.
Accuracy of Plagiarism Detection
PlagAware effectively identifies plagiarized content and can detect full-text matches. It achieved an average detection rate of 57% across multiple sources, ranking second behind Scribbr (88%).
However, its performance declines when analyzing heavily edited text or Free plagiarism within academic sources.
Pros:
- Online reports feature color-coded highlights for easy interpretation.
- Detects more instances of Free plagiarism compared to most competitors (second only to Scribbr).
- Ensures user privacy by not storing or selling submitted documents.
Cons:
- Limited to a one-time free trial before requiring payment.
- PDF reports are difficult to read due to formatting limitations.
- Performs poorly when analyzing scholarly sources.
User Experience
The online report is user-friendly, featuring color-coded indicators that differentiate sources and display similarity percentages for flagged sections. Additionally, a dashboard retains a history of previous scans for easy reference.
However, the tool does not preserve the original document’s formatting, and the downloadable PDF report lacks color differentiation, making it less intuitive.
Data Privacy and Support
PlagAware ensures user privacy by allowing documents to be deleted from profiles at any time. Customer support is available via a contact form and phone number, though live chat assistance is not provided.
3. Scribbr: The Leading Plagiarism Checker
Free Version Availability
Scribbr provides a limited free version, ideal for determining whether a document contains potential plagiarism. However, to access the complete report, users must upgrade to the premium version, which ranges from $19.95 to $39.95 based on word count. There are no word limits on uploads, allowing for comprehensive document analysis.
Plagiarism Detection Quality
Scribbr outperforms both free and paid alternatives in detecting plagiarism, identifying 88% of copied content compared to an average of 43% among other tools.
It excels in recognizing plagiarism from academic sources such as journal articles and dissertations. Additionally, Scribbr demonstrates superior capability in detecting Free plagiarism within paraphrased or heavily edited text, where other tools often fall short. Unlike many alternatives that provide only partial matches, Scribbr consistently links entire plagiarized passages to their original sources.
Pros:
- Offers a limited free version
- Detects significantly more plagiarism than competing tools
- Identifies Free plagiarism even in extensively edited texts
- Ensures data privacy—documents are neither stored nor sold
- Provides a money-back guarantee with live customer support
- Features a Self-Plagiarism Checker for detecting duplicate content in personal documents
Cons:
-
A premium subscription is required to access the full plagiarism report and precise similarity score
User Experience
Scribbr delivers results in an easy-to-read downloadable report, with different sources highlighted in distinct colors for enhanced clarity.
To assist users in correcting issues, the platform integrates with Scribbr’s Citation Generator, which provides properly formatted citations where necessary.
An added advantage is the Self-Plagiarism Checker, which allows users to compare their unpublished work against public databases to identify potential self-plagiarism. However, users cannot edit documents directly within the tool, and rechecking a document requires a separate scan.
Data Security & Customer Support
Scribbr prioritizes data security by ensuring that uploaded documents are not stored, sold, or shared. Files are automatically deleted after 30 days, though users have the option to delete them manually after analysis.
Live customer support is available in multiple languages, offering assistance as needed. Additionally, Scribbr provides comprehensive Free plagiarism resources, including guides on proper citation practices.
A notable feature is Scribbr’s Happiness Guarantee, which allows users to request a free recheck or a refund if they are unsatisfied with the service.
4. DupliChecker
Pricing
DupliChecker offers a free plagiarism detection service, with a limit of 1,000 words per scan. Users who require higher limits can opt for premium plans, which allow scans of up to 25,000 words. However, the wide range of subscription options can be confusing to navigate. The most affordable plan starts at $10 per month.
Accuracy of Detection
DupliChecker successfully identified over 40% of plagiarized content, including modified text. However, it struggled to detect exact matches, often highlighting only fragments of plagiarized sentences rather than entire passages.
Pros:
- Free for up to 1,000 words per scan
- Does not store uploaded documents
- Reports are relatively user-friendly
Cons:
- Advertisements for other services can be distracting
- Detects a lower percentage of plagiarism compared to competitors
- Only identifies partial matches rather than full sentence matches
- Lacks color coding to differentiate sources
User Experience
The interface is cluttered with advertisements, making navigation and execution of plagiarism checks somewhat challenging. Additionally, both online and downloadable reports highlight plagiarized text in a single color, making it difficult to associate flagged text with specific sources.
Data Privacy & Support
DupliChecker states that it does not retain uploaded documents and deletes content immediately after the scan to prevent data leaks. While the platform lacks live customer support, users can reach out via a contact form on the website.
5. Prepostseo
Free Version Availability:
Prepostseo’s free version allows users to scan up to 1,000 words per session and conduct up to 30 search queries per month (one search query corresponds to a single sentence), as stated on the company’s website. However, during our testing, the search query limit did not appear to be enforced.
The most affordable paid plan, priced at $10 per month, increases the limit to 5,000 words per search and 5,000 search queries.
Accuracy of Matches:
While Prepostseo occasionally detected full-text matches, it primarily identified partial matches, similar to other free plagiarism detection tools. The tool generally attributed plagiarized content to the correct sources and maintained a consistent performance across various levels of editing.
Pros:
- Utilizes color-coded highlighting to differentiate types of plagiarism.
- Identifies some full matches.
- Includes a citation assistance feature.
Cons:
- Detects a relatively low percentage of plagiarism.
- The downloadable report is difficult to interpret.
- Color coding does not differentiate between multiple sources.
Usability:
The platform differentiates verbatim plagiarism from paraphrased content through color-coded highlights; however, its classification was frequently inaccurate. Additionally, identical colors are used for different sources, making it difficult to interpret reports. The downloadable PDF report does not indicate the specific sources of plagiarized content.
Although the platform provides tools to help eliminate plagiarism, their effectiveness was inconsistent.
Trustworthiness:
Prepostseo asserts that it does not store or sell user documents. While the website includes a support request form, it does not offer live customer support.
6. Copyleaks: Plagiarism Detection and Analysis
Free Trial and Pricing
Copyleaks offers a one-time trial for up to 2,500 words, which requires users to create an account to access the results.
Beyond the trial, a subscription is necessary to continue using the service. Pricing starts at $16.99 per month for 100 credits (with each credit covering 250 words). Annual plans are available from $13.99 per month for 1,200 credits.
Accuracy and Detection Performance
Copyleaks demonstrated limited effectiveness across various source types, identifying an average of only 38% of plagiarized text. While it occasionally attributed entire passages to the correct source, it primarily detected only partial matches.
Pros:
- Maintains original document formatting within the online tool
- Online reports provide clear alignment between plagiarized content and its sources
Cons:
- Limited to a single free trial
- Downloadable reports make it challenging to cross-reference text with sources
- Underperforms in detecting Free plagiarism in academic sources
- Data protection policy lacks clarity
Usability and User Experience
The downloadable report lists all sources at the top, making it difficult to cross-reference them with the identified text.
The online version is more user-friendly but requires users to click each sentence individually to view its source. The tool categorizes detected plagiarism into “identical,” “minor changes,” and “paraphrased” text, though these classifications are frequently inaccurate.
Data Security and Customer Support
Copyleaks asserts that it does not misuse user content. However, users must contact customer service to request the permanent removal of their files. The platform provides support through a contact form and a live chat option.
7. Check-Plagiarism Review
Free Version and Pricing
Check-Plagiarism offers free scans for up to 1,000 words. According to the website, guest users are limited to 50 search queries per month (where one sentence equals one query). However, this restriction was not clearly enforced during testing.
Paid plans are available for higher limits:
- Weekly plan: $6.99/week (up to 10,000 words)
- Monthly plan: $17/month (up to 35,000 words)
Accuracy of Plagiarism Detection
Check-Plagiarism detected an average plagiarism rate of only 37%, which is relatively low compared to other tools. Its performance was particularly weak when analyzing scholarly sources or edited content.
While the tool successfully identified some full matches, it primarily detected partial matches, limiting its effectiveness for comprehensive Free plagiarism checks.
Pros:
- Allows uploads of up to 1,000 words per scan
- Online report effectively matches plagiarized content with its source
Cons:
- Difficult to match text with sources in the downloadable report
- Different sources are highlighted in the same color, making differentiation challenging
- Scans content sentence by sentence, often failing to detect full matches
- Website contains numerous ads that interfere with usability
Usability
The downloadable report presents a long list of sources, making it difficult to cross-reference them with the highlighted text.
The online version of the report provides a slightly better user experience by displaying a box next to the plagiarized text that shows the corresponding source. However, the website’s heavy presence of ads negatively impacts usability.
Additional features include:
-
A “rewrite” function that replaces words but does not effectively eliminate plagiarism
-
A manual citation tool for referencing sources
Trustworthiness
Check Free Plagiarism states that uploaded documents are not stored or shared with third parties.
The website provides an FAQ section, though the answers are somewhat unclear. Customer support is limited to a contact form, with no live chat or direct assistance available.
8. Plagiarism Detector: Comprehensive Review
Pricing and Accessibility
Plagiarism Detector is available for free without requiring user registration, but it imposes a 1,000-word limit per document. Users can increase this limit to 25,000 words by opting for a paid plan.
Accuracy and Quality of Matches
The tool detected only 35% of the plagiarized content in testing, with particularly weak performance when analyzing scholarly sources and heavily edited texts. It primarily identified partial matches, often attributing individual sentences to multiple sources rather than detecting full passages.
Pros:
- Free to use (up to 1,000 words per document)
- Ensures document privacy (no storage or resale of submitted content)
Cons:
- Technical issues when analyzing longer documents
- Difficulty in matching text with sources within reports
- Different sources are highlighted in the same color, leading to confusion
Usability and User Experience
The downloadable reports generated by Plagiarism Detector can be challenging to interpret due to inconsistent color-coding, where different sources are highlighted in the same color. Additionally, hovering over flagged text does not display the corresponding source, requiring users to manually locate it in a separate list.
The online report offers slight improvements—clicking on a sentence reveals its source. However, the original document’s formatting is not preserved, which may hinder readability.
Trustworthiness and Support
Plagiarism Detector explicitly states that it does not store or sell submitted documents, ensuring user privacy. While live customer support is unavailable, users can submit inquiries through a help request form.
9. Small SEO Tools Review
Small SEO Tools offers a free plagiarism detection service with a word limit of 1,000 per scan. While it provides various document upload options and ensures user files are not stored in its database, its effectiveness and usability present some limitations.
Pricing and Accessibility
Small SEO Tools is free, allowing users to check up to 1,000 words at a time. Users needing to scan larger texts can conduct multiple checks, but the website enforces CAPTCHA verification for each upload.
Accuracy and Reliability
In testing, Small SEO Tools identified an average of only 44% of plagiarism, making it significantly less effective than other Free plagiarism detection tools. Its approach of scanning individual sentences rather than full documents often results in incomplete matches. Additionally, scan results varied when the same document was checked multiple times, raising concerns about the tool’s consistency and reliability.
Pros:
- Free to use (up to 1,000 words per scan)
- Supports multiple document upload formats
- Does not store documents in its database
Cons:
- Detects a low percentage of Free plagiarism
- Slow performance with a somewhat cluttered interface
- Scans sentences individually rather than analyzing full texts
User Experience and Features
While the tool itself is functional, the website is cluttered with advertisements. The Free plagiarism report clearly links matched text with identified sources, though it uses only one color per source, which can make analysis more difficult.
Small SEO Tools also features an AI-powered paraphrasing tool, accessible via a “Remove Plagiarism” button. However, this tool primarily substitutes words rather than restructuring sentences, failing to effectively eliminate Free plagiarism.
The downloadable PDF report is difficult to read due to poor formatting retention and the absence of direct links between flagged text and sources.
Data Privacy and Support
Small SEO Tools asserts that all uploaded files are deleted immediately after scanning. Users can access the service without registration. However, customer support options are limited to a contact form, with no dedicated support team or live assistance available.
10. Quetext Review
Quetext is a plagiarism detection tool that offers a built-in citation assistant, ensuring proper attribution of sources. It provides a secure environment where submitted documents are not stored in a database. While the platform offers support options, live customer support is not available.
Pricing and Free Trial
Quetext offers a free trial that allows users to check up to 500 words. Beyond this limit, users must subscribe to a premium plan, which starts at $7.20 per month. Higher-tier plans are available for those who require increased word limits, with the base plan covering up to 100,000 words.
Detection Accuracy
In testing, Quetext identified 48% of plagiarized content. However, the tool struggled to match entire excerpts to their respective original sources. Instead, different sentences were attributed to various sources, and, on occasion, incorrect attributions were made.
Pros:
- Integrated citation assistant helps identify and add missing citations.
- Documents are not stored in a database, ensuring user privacy.
- Support options are available (though live support is not provided).
Cons:
- Detects partial matches rather than complete source attribution.
- Requires a monthly subscription of at least $7.20 after the free trial.
- Limited effectiveness for scholarly sources.
Usability and Reporting
Quetext’s online and downloadable reports significantly alter the formatting of the original text, which may impact readability. Additionally, the tool does not differentiate sources using distinct colors. Instead, it highlights partial matches in orange and full matches in red, making it difficult to trace specific sources.
While the built-in citation assistant aims to assist users in addressing Free plagiarism, it has limitations. Citations generated by the tool may not always be accurate, often requiring manual input to ensure correctness.
Privacy and Support
Quetext emphasizes user privacy, stating that it does not store submitted text in a database. All content remains private and encrypted.
Customer support is available through an FAQ section on the website, along with a request submission form for further assistance. However, live customer support is not provided.
