Duplicate content is unacceptable, whether submitting a research paper or publishing website content. Universities can penalize students for plagiarism. Also, professionals may face legal trouble due to copyright infringement.
So, what’s the solution? How do you ensure originality?
Plagiarism checker tools solve this problem. They automatically detect copied or similar content by crawling vast online databases. Once flagged, you can edit those sections to make your content truly original.
The best part? You don’t need to spend a huge amount. There are plenty of free tools that offer features comparable to paid ones. Today, we’ve compiled a list of the Best Free Plagiarism Checker Tools to help you provide authentic content.
Let’s check them out—one by one!
What is a Plagiarism Checker?
Plagiarism means copying someone else’s work and presenting it as your own without giving credit. You can copy written text, speeches, artwork, or even code. Plagiarism checker tools help identify such similarities. It allows users to maintain originality.
How do online plagiarism checker tools work? These tools use advanced database software that scans your content. Then, it compares your content against web pages, academic papers, and other indexed sources.
The tool crawls and analyzes online content to detect exact matches, partial similarities, and paraphrased material. It then generates a detailed report highlighting matched sections along with percentages.
| Tools | Free Limits | File Upload Options | Speed | Accuracy | Best For |
| Copyleaks | No limits | DOC, Text, PDF, URL | Fast | High | Scholars and Marketing professionals |
| SmallSEOTools | 1000 words/ search | PDF, DOC, Text, Upload from Drive & Dropbox | Depends on the word count | High | Bloggers and Freelance Writers |
| Duplichecker | 1000 words/ search | PDF, Text, DOC, URL, Upload from Drive & Dropbox | Depends on the word count | High | Freelancers and Educators |
| PapersOwl | No limits | Text | Fast | High | Students and Researchers |
| Plagiarism Detector.net | 1000 words/ search | Text, PDF, DOC, URL, Upload from Drive & Dropbox | Slow | Moderate | SEO professionals and Content writers |
| Quetext | 500 words/ search | Text | Fast | Moderate | Publishers |
| PrePostSEO | 1000 words/ search | Text | Fast | Moderate | SEO Teams |
| PaperPal | 7000 words/ month | PDF, DOC | Slow | Low | Academics and Educators |
| PaperRater | 10 documents/ month | DOC, Text, PDF | Slow | Low | Beginner and School students |
Testing Parameters
To evaluate the best free plagiarism checkers, I selected two test documents. Although each document contains fewer than 150 words, I also tested longer content on each tool to better assess their speed and performance.
These test documents were minimally edited using artificial intelligence. The content was copied from Wikipedia and other online sources to simulate realistic plagiarism cases.
I considered the following factors during testing:
- Accuracy in detecting plagiarized content
- Speed of analysis
- File upload options and formats supported
- Availability of AI content detection
- Free usage limits
I excluded tools that only offer free trials, as they are not practical for regular use by students, freelancers, or budget-conscious users.
1) Copyleaks – Best for AI-based Plagiarism Insights
Copyleaks is already well-known among content writers as a reliable AI content detection tool. At the same time, it performs impressively in checking plagiarized content as well. The tool was launched in 2015 by Alon Yamin and Yehonatan Bitton.
Copyleaks uses advanced AI to detect plagiarism in code, text, images, and AI-generated content. Once you upload your files, it generates a detailed report with text similarity (matched text) and originality, highlighting the matching results.
Plagiarized sections are color-coded, with sources and clickable links. They even provide individual similarity percentages. You’ll also receive content similarity insights categorized as identical match, minor changes, paraphrased, and original text.
Pricing
Copyleaks’ free version allows unlimited document scans, but it does not display all matching sources and links. To unlock full reports and access advanced features like cross-language plagiarism detection and multiple forms of paraphrasing recognition, you’ll need to subscribe to a paid plan starting at $107.88/year.
Downsides
- Free version does not reveal all matching sources
- No citation-generation feature
Ideal for
- High-school students needing detailed originality reports
- Scholars, educators, and marketing professionals seeking a strong AI-powered plagiarism check
2) SmallSEOTools – Best for SEO-focused Analysis
If you don’t want to use the paid version of Copyleaks, a great free alternative is SmallSEOTools by Tausif Akram. This tool entered the market before Copyleaks, in 2010. And it became a favorite among website owners, developers, and content experts as it performs on par with many paid plagiarism checkers.
SmallSEOTools scans billions of web pages using its database software. I’ve personally used it for years to get detailed reports on both exact and partial content matches. Unlike Copyleaks, it provides all matched source URLs along with sentence-by-sentence results.
You can upload PDFs, Word documents, or even pull files directly from Google Drive or Dropbox. The tool doesn’t store your data, so your content remains secure and protected.
It also allows you to exclude specific URLs, give word count statistics (like unique words and average sentence length), and include a citation assistant.
Pricing
You can scan up to 1,000 words per document for free, with no limit on the number of documents. The Pro version starts at $4.99/week, allowing scans of up to 10,000 words or 33 pages, and unlocks features like advanced plagiarism detection, multiple file uploads, and multi-layer search capabilities.
Downsides
- Can be slow with long-form content
- CAPTCHA verification fails occasionally
- Deep web scanning is only available in the paid version
Ideal for
- Bloggers needing SEO-focused tools like keyword research and backlink analysis
- Freelance writers looking for reliable free plagiarism checks
3) Duplichecker – Best for User-friendly Interface
Duplichecker is another solid alternative to SmallSEOTools, launched in 2006. It offers a range of useful free tools for proofreading and online content editing. Tools like the plagiarism checker, paraphrasing tool, and backlink checker help improve search engine optimization.
The plagiarism report is similar to that of SmallSEOTools. It highlights both exact and partial matches using color-coded text. Red highlights show exact matches, while yellow highlights show partially matched content.
You’ll also get a brief word stats report, where you can check word count, syllables, read time, and more. Duplichecker supports various formats, including PDF, Word documents, and files from Google Drive or Dropbox.
Pricing
There’s no limit on the number of documents you can scan. However, free users can only scan up to 1,000 words at a time. To access 10,000 words per search, the advanced plagiarism checker, and custom reports, you can upgrade to the Basic II plan for $5/week.
Downsides
- CAPTCHA verification can be time-consuming
- No citation generation feature
- Frequent ads may affect user experience
Ideal for
- Freelance writers for proofreading and SEO optimization
- Educators needing multiple free plagiarism checks daily
4) PapersOwl – Best for Academic Use with Writing Help
PapersOwl isn’t as popular as Copyleaks or SmallSEOTools, but it’s still a well-performing plagiarism checker, especially for academic use. Apart from plagiarism detection tools, it offers multiple free writing tools, including a thesis statement generator, a conclusion generator, and a citation generator.
When you upload content, PapersOwl provides a color-coded plagiarism report, similar to Copyleaks. The report includes two key insights: the percentage of similarity and the percentage of originality in your content. It also lists matching sources with clickable links.
PapersOwl allows users to exclude specific URLs from the scan results, making it easier to tailor reports. The tool is extremely easy to use and delivers quick results. Hence, it’s ideal for students and academic purposes.
Pricing
PapersOwl’s tools are completely free for everyone. It provides high-quality plagiarism checks with all matched sources and no word limits, at no additional cost.
Downsides
- Offers only basic insights on plagiarized content
- No detection of partial plagiarism or paraphrased text
Ideal for
- Students looking for a user-friendly plagiarism checker
- Researchers in need of academic tools like citation and thesis generators
5) Plagiarism Detector.net – Best for Basic Plagiarism Reports
Another lesser-known plagiarism detector I used earlier is Plagiarism Detector.net. This tool offers deep search capabilities for free and is extremely beginner-friendly with a clean, intuitive interface.
You can easily copy/paste your content, upload PDFs or text files, pull files from Dropbox or Google Drive, or even paste a URL. The report is visually simple and color-coded with three key insights: Green text shows unique content, Blue text highlights partial matches, and Red text shows exact matches.
The tool also lets you exclude specific URLs and generate citations. However, the detection results are not always accurate compared with more advanced tools like Copyleaks or SmallSEOTools. In some tests, I received different results when checking the same content multiple times.
Pricing
Plagiarism Detector.net is completely free for scanning up to 1,000 words per check. To unlock more features, such as checking up to 36,000 words, 1,200 pages, URL-based searches, and downloadable reports, you can subscribe to the Student Plan for $96/year.
Downsides
- No advanced insights like paraphrased content or word statistics
- Takes more time to scan long-form blogs, articles
Ideal for
- Beginners needing quick plagiarism checks for short-form content
- Content writers and SEO specialists checking website content
6) Quetext – Best for Quick Copy-Paste Checks
Quetext, another reliable plagiarism detection tool, was introduced in 2010 by Nicholas D. The platform uses DeepSearch technology to assess the originality of content. You can use the tool without signing up, making it quick and accessible.
The tool provides a straightforward plagiarism report with a percentage-based similarity index. It highlights plagiarized text in red, and on the right-hand side, you’ll see clickable source links.
By clicking the dropdown menu under each source, you can view the exact text that was flagged, also highlighted in red. Plus, Quetext allows you to cite sources and view the individual similarity index for each match.
Pricing
Quetext’s free plan lets you check up to 500 words per document. To unlock features like bulk file uploads (up to 20 files), scanning up to 100,000 words, and access to the Grammar Checker, you can subscribe to the Essential Plan at $167.88/year (equivalent to $13.99/month).
Downsides
- Only text file uploads are allowed in the free version
- Does not detect partial plagiarism
- All plagiarized text is highlighted in the same color, with no distinction between exact and partial matches
Ideal for
- Freelance writers checking short-form content quickly
- Publishers who need bulk uploads with the paid version
7) PrePostSEO – Best for Content Proofreading and Optimization
PrePostSEO offers 20+ online tools designed to help writers, students, and marketers publish unique, optimized content. The user interface is well-designed, allowing you to check plagiarism, humanize content, remove duplicate content, and download reports, all from a single dashboard.
You can either paste your text or upload a PDF/DOC file. The platform scans your document in just a few seconds and generates a report showing two key insights: % Plagiarized Content and % Original Content.
Only the plagiarized text is highlighted in red. PrePostSEO also provides all matching sources with links and individual similarity percentages. Additional options for power users include Exclude links and Exclude quotes.
Pricing
The free version of PrePostSEO allows you to scan up to 1,000 words per document. For scanning up to 5,000 words per submission, deep search, and an ad-free experience, you can opt for their All-in-One Basic Plan, which costs approximately $50/year or $4.17/month.
Downsides
- No detailed plagiarism insights (e.g., partial matches, paraphrased content)
- Exclude links option is not available in the free version
- No separate pricing plans for the plagiarism checker
Ideal for
- SEO teams and digital marketers looking for an SEO toolkit with plagiarism detection
- Content writers who want to verify and optimize content on one platform
8) PaperRater – Best for School Students
For quick originality checks, PaperRater suits well. It provides instant plagiarism reports. The platform uses a combination of machine learning, natural language processing, computational linguistics, information retrieval, and data mining technologies.
You can either upload a file or paste text directly. The report highlights plagiarized content and provides an originality index. It clearly identifies the original sources and displays percentage matches for detected plagiarism.
However, the tool limits the number of document scans, which may not be sufficient for professional or frequent use. Also, if a piece of plagiarized content matches multiple sources, the tool will only show one source and omit the others.
Pricing
PaperRater’s free version supports up to 10 document uploads per month. The Premium plan costs $7.95/month or approximately $95/year, and includes up to 20 pages per submission, 200 pages total, and 25 plagiarism checks per month.
Downsides
- No overall plagiarism percentage provided
- Often cannot check plagiarism for long-form content
- Only 10 document submissions are allowed monthly for free
Ideal for
- Beginners seeking instant feedback on writing
- Students who need a combined grammar and plagiarism checker
9) PaperPal – Best for Research Paper and Academic Editing
PaperPal is primarily an academic writing tool that also offers a free plagiarism checker. It supports long-form content (up to 7,000 words). The platform is trusted by over 4,000 journals and used by 2 million+ academics globally.
To use the tool, you must sign up and create an account on their website. Once logged in, you can upload your file. The tool will automatically scan and generate a plagiarism report.
However, I found the free plagiarism report quite basic. It provides a similarity percentage but does not offer clickable source links. While it lists individual similarity ranges, not all sources are shown in the free version.
Pricing
PaperPal’s free plan allows users to check up to 7,000 words per month (approximately 25 pages). To scan up to 10,000 words/month and unlock detailed reports with full source details, you can upgrade to the Prime Plan at ₹582/month.
Downsides
- Free version doesn’t show all plagiarism sources
- Only supports DOC and PDF files (no plain text support)
- Sources are listed without clickable links
- The plagiarism report lacks advanced insights (e.g., exact match, partial match, originality breakdown)
Ideal for
- High school and university students checking long-form essays for plagiarism
- Researchers and scholars need detailed reports for thesis writing
Plagiarism is considered a serious offense in both academia and web content creation. You can’t simply copy someone else’s work without giving proper credit. However, manually checking for plagiarism is nearly impossible, and that’s where plagiarism checker tools come in. Here’s how they help:
1) Quick Detection
Premium plagiarism detection tools like Copyleaks, SmallSEOTools, and Duplichecker use advanced algorithms and AI-powered technology. They scan vast databases and detect similarities within minutes, saving time and effort.
2) Prevent Duplicate Content
Duplicate content is harmful to SEO. Copywriters and content managers use these tools to detect partial or exact matches in their content. It helps them avoid Google penalties and maintain better rankings.
3) Ensure Academic Integrity
Universities do not tolerate copied content and strongly promote ethical writing practices. By using free plagiarism detection tools, students can avoid accidental plagiarism before submitting assignments or papers.
4) Find Citation Sources
Plagiarism checkers don’t just highlight copied content—they also identify the original sources. Tools like SmallSEOTools and Duplichecker even offer built-in citation generators, making it easy for students to credit sources in their assignments or research papers.
Why Should You Trust Me?
As someone who has been working in the digital space since 2015, I’m always on the lookout for useful SaaS tools that make work easier and more efficient. Through my content, I aim to help beginners, small businesses, freelancers, and startups get more done using reliable digital products.
You’ll find my honest reviews on tools like the best AI tools for research, top AI note-taking apps, free email marketing tools, and more. While managing my own website content, I regularly use plagiarism checker tools to ensure originality and maintain content quality. This has given me the opportunity to test and use multiple free plagiarism tools hands-on.
This article is based on my real experience. I curated a list that will genuinely help writers, students, and researchers discover plagiarism checkers that maintain high accuracy even if it’s free.
Conclusion
Plagiarism checkers don’t just detect copied content; they play a vital role in maintaining originality and brand authenticity. For students, these tools encourage ethical writing practices by ensuring their work is properly cited.
In our review, the 9 best free plagiarism checker tools proved to be accurate and reliable. Copyleaks is highly recommended for academic and professional use. If you need access to all source links, tools like SmallSEOTools and Duplichecker are great choices.
If you also want to detect AI-generated content, don’t forget to check out the 12 Best AI Content Detection Tools in 2025 (Free + Paid).
That’s all for today! Let me know which tool you personally use or find most helpful. Until then, I’ll continue exploring and bring you more informative content next time.
FAQs
Are plagiarism checkers accurate?
Accuracy depends on the individual tool. Not all free plagiarism checkers provide highly accurate results. It largely depends on the tool’s database size and the algorithms used to detect copied content. However, you can trust the tools reviewed in this article, as I’ve clearly mentioned the accuracy level of each one based on hands-on testing.
Which database do plagiarism checker tools compare?
Plagiarism checkers compare your content against multiple sources. These include websites and blogs, online articles, journals, academic databases, digitized books, research papers, published materials, and internal proprietary databases (used by platforms like Copyleaks).
Can plagiarism checkers also improve my writing?
Absolutely! Beginners can scan documents with plagiarism checkers and rephrase the flagged content to improve writing skills. Over time, they will get better at maintaining originality, credibility, and adhering to ethical writing standards.
How often should I use a plagiarism checker?
Every time you write something for submission or publication, it’s best to use a plagiarism checker before final submission and during revisions to catch issues early. This habit ensures your content stays original and professional.
