Free Plagiarism Checker
Find sentences copied from the web before you submit or publish. See how much of your text is online and where. 1,000 words free, no sign-up.
Text to Check
What is a plagiarism checker?
A plagiarism checker is a tool that compares your text with content that already exists, to find sentences that were copied without credit. HumanizerPRO's free plagiarism checker searches live web results for sentences from your text, compares the pages it finds with every sentence, then shows how much of your text was found online, which sentences matched and the pages they match.
Use it to find copied sections, missing citations and passages you pasted from a source and forgot to rewrite. Since it searches what's on the open web right now, it works best for blog posts, articles, web copy and essays that draw on online sources.
- Free
- 1,000 words per scan, no sign-up
- Paid plans
- Up to 5,000 words per scan
- Results
- Share of your text found online, matched sentences and source links
- History
- Your last 30 scans, saved only in your browser
How the plagiarism checker works
Click a step to see what happens to your text.
How to check for plagiarism
A scan takes a few seconds. Here's how to run one with HumanizerPRO.
- 1
Paste your text
Paste or type at least 50 characters, or upload a file. Without an account you can scan up to 1,000 words at a time.
- 2
Click Check Plagiarism
Or press Ctrl+Enter. Results usually arrive in a few seconds.
- 3
Review the matches
Check the highlighted sentences and open the source pages next to them to see where the text appears.
- 4
Rewrite or cite
Put matched passages in your own words, or quote them and add a citation. Then rescan.
Does it find copied text? We tested it
In October 2026, the HumanizerPRO team ran 18 texts through the plagiarism checker: 5 paragraphs copied word for word from Wikipedia, 5 lightly reworded copies of them, 5 original texts, and 3 original texts with a copied Wikipedia paragraph added at the end.
Word-for-word copies caught, each scored 94% to 100% found online.
Copied paragraphs hidden at the end of an original text found (42% to 60% of the text).
Original texts with nothing flagged. The fifth had one common sentence that appears word for word on several websites.
Lightly reworded copies were harder: 2 of 5 were partly caught. Like most web checkers, it finds copied and closely copied text best. Learn more in our AI plagiarism guide.
What you get with this plagiarism checker
A quick, clear originality check with sources you can verify.
Sources for every match
Every matched sentence links to the web page it was found on, so you can see it in context.
Highlights in your text
Matched sentences are highlighted right in your text, together with the sentences that were checked.
Checks the whole text
Searches are spread from the first paragraph to the last, and every sentence is compared with the pages found.
Scan history
Your last 30 scans are saved in your browser, with a search box. Nothing is saved to an account.
Paste, type or upload
Upload .txt and .md files, or try the sample text to see a scan.
Free, no sign-up
Scan up to 1,000 words at a time for free. Paid plans raise the limit to 5,000 words.
What a free plagiarism check can't see
This checker searches the public web. It can't see private student paper archives, paywalled journals or documents that aren't online. It searches a sample of your sentences (about one for every 40 words), so a copied sentence on a page none of the searches found can be missed.
It finds copied and closely copied sentences best. Heavy paraphrasing or AI rewriting can hide where an idea came from: in our test, only 2 of 5 lightly reworded copies were partly caught. Cite your sources even when you've changed the words. To check whether text was written by AI rather than copied, use our free AI detector.
Who uses this plagiarism checker
Students
Catch missing citations and copied lines before you hand in an essay.
Writers and bloggers
Make sure a post is original before you publish it.
SEO and content teams
Check freelance and AI-assisted articles for copied web content.
Teachers
Spot passages copied from the web and see where they came from.
More free tools
Frequently asked questions
Is this plagiarism checker free?
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Yes. You can scan up to 1,000 words at a time for free, with no account and no sign-up. Paid plans raise the limit to 5,000 words per scan.
How does the plagiarism checker work?
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It searches about one sentence for every 40 words as an exact phrase in live Google results, then opens the pages it finds and compares them with every sentence of your text. Copied sentences are highlighted, with links to the pages they appear on and how much of your text was found online.
Does it show the sources?
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Yes. Every matched sentence comes with the web pages it was found on, and you can click through to see them in their full context.
Can it check for AI-generated text?
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No. A plagiarism checker looks for copied text, and AI text is usually new text, so it won't show up as copied. To check for AI writing, use HumanizerPRO's free AI detector.
Is it the same as Turnitin?
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No. Turnitin also compares work with its private archive of student papers and publications. This checker searches the open web, so use it to catch text copied from websites before you submit.
What does the score mean?
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It shows how much of your text was found online. 0% means nothing was found, and 40% means about 40% of your text matches pages on the web. Open the sources to decide whether you need to rewrite or cite.
Is my text saved?
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Your scan history is stored only in your own browser, and you can delete it whenever you want. HumanizerPRO doesn't save the text you scan to an account.
How do I fix plagiarism in my text?
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Rewrite matched passages in your own words and cite the source, or quote them exactly with a citation. Then scan again to make sure nothing is left.