🔍 Plagiarism Checker

Video Guide: 🔍 Plagiarism Checker

Video guide with full transcript

About 🔍 Plagiarism Checker

The Plagiarism Checker compares your text with public web pages. It picks the most distinctive passages of your text, searches Google for each one as an exact phrase, opens every page it finds and compares your whole text with it. Every sentence that also appears online is highlighted and numbered, and each source shows how much of your text it contains, with a link to the page. A second, free check looks for repetition inside your own text and runs entirely in your browser.

How the Web Check Works

1. Passages are chosen from across the text. Runs of 9 to 20 words are taken from sentences at the beginning, middle and end, at least four and up to eight for every 6,000 characters. Shorter phrases still match when a source has been lightly edited.
2. Google is searched for each passage as an exact phrase. A page that contains the passage word for word becomes a candidate source.
3. Every page found is opened and compared with your whole text. The comparison works six words at a time, and a run of eight or more matching words counts as a match. A page found through one passage therefore also reveals every other sentence copied from it.
4. You get the result: the share of your text found online, each matching sentence highlighted with the number of its source, and the list of sources, each with the share of your text it contains and its longest matching passage.

Reading the Result

• Solid highlight (confirmed): the page was opened and the same words were found on it.
• Dashed highlight (found by search): Google matched the passage on that page, but the site would not let the checker open it, which is common for social networks, paywalled sites and some forums. Open the link to see the page yourself.
• Found online: the share of your words that appear on at least one source. Quotations you have cited correctly show up too; the check cannot tell a cited quote from a copied one.
• What was searched: the passages sent to Google, each marked as matched or not matched.

What It Cannot See

The web check covers public pages in Google's index. It cannot see private collections such as Turnitin's archive of student papers, journals behind a paywall or pages Google has not indexed, and it does not detect paraphrasing that changes most of the words. "No matching pages" means that none of the passages searched turned up online. It is not proof that a text is original.

Cost

Each web check costs 1 AI credit per 6,000 characters (about 1,000 words), up to 30,000 characters per check. Everyone gets 3 free AI credits a day, and you are only charged when the check returns a result: if the search fails, the credit goes back to you. Checking the same text again within an hour is free. Pro and Premium plans include monthly AI credits, and credit packs are available for occasional use. The quick repetition check is free and unlimited.

The Quick Repetition Check

The second button looks only inside your text. It scores each sentence for repeated phrases and duplicate sentences and reports vocabulary variety and sentence-length variation. Because it never compares your text with anything else, it cannot tell you whether a text was copied. Use it to tidy up a draft, and use the web check to find sources.

Who Uses It

• Students checking an essay before submission, to find sentences that need quotation marks and a citation.
• Teachers checking a suspicious passage in a student's work against the public web.
• Writers, editors and site owners checking that an article is not already published elsewhere, or finding sites that copied their own work.

Tips for Avoiding Plagiarism

• Quote and cite: when you use someone's exact words, put them in quotation marks and name the source.
• Paraphrase properly: restate the idea in your own words and sentence structure, then still cite the source of the idea.
• Write from understanding: read the source, close it, and write from memory; this produces naturally original wording.
• Keep your notes separate: mark copied passages in your notes so they do not slip into the draft unquoted.

Frequently Asked Questions

Q: How does this plagiarism checker work?

It picks the most distinctive passages of your text, searches Google for each one as an exact phrase, opens every page it finds and compares your whole text with each page. Every sentence that also appears on a page is highlighted and numbered, and each source shows how much of your text it contains.

Q: Is this plagiarism checker free?

Yes, within a daily allowance: everyone gets 3 free AI credits a day, and a web check costs 1 AI credit per 6,000 characters (about 1,000 words). You are only charged when the check returns a result. The quick repetition check is free and unlimited. Pro and Premium plans include monthly AI credits for more checks.

Q: Does it check Turnitin or academic databases?

No. It searches public web pages in Google's index. It cannot see private collections such as Turnitin's archive of student papers, journals behind a paywall, or pages Google has not indexed.

Q: Is my text stored or shared?

The quick repetition check runs entirely in your browser. For the web check, your text is sent to our server, which sends the selected passages to Google Search through the Gemini API and compares your text with the pages found. The result is kept for one hour so that checking the same text again is free; it is not stored after that.

Q: How accurate is it?

Word-for-word copying from a public web page is found when one of the passages searched comes from that page, and every other sentence copied from the same page is then found as well. Heavy paraphrasing, copying from offline or private sources, and very short texts are not reliably detected, so "no matching pages" is not proof that a text is original. Every match shows the words it is based on and links to the page, so you can check it yourself.

Q: Can I check a whole class's essays at once?

Yes. Open Check a whole class under the checker, add each student's file (.txt, .docx or .pdf) or paste the texts with a line of three dashes between them, and press Check all. Up to 30 texts are checked one after another against the web, each costing the same credits as a single check. The results come in one table with the matched percentage and the top sources of every text, and you can download it as a CSV file for your gradebook.

Q: Why is a passage I quoted marked as a match?

Because it is on the web. With "Leave out quoted text and the reference list" ticked (it is on by default), passages in quotation marks and the reference list at the end are shown in grey and do not count towards the percentage. A quotation without quotation marks still counts as a match, so mark and cite every quotation.

Additional Resources

• Plagiarism - Wikipedia
• Plagiarism Detection - Wikipedia

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