Free Chrome™ extension · AI detector · Plagiarism checker · Citations

AI Detector & Plagiarism Checker for Chrome

Plagiarism Checker Plus puts an AI detector, a plagiarism checker and a citation generator in Chrome’s side panel. Check what you are writing in any text box, check text you highlight on a page, and cite the page you are reading — without copying anything into another tab.

Coming soon to the Chrome Web StoreTry the web app
Free to installWorks as a guestText sent only when you click Check
Plagiarism Checker Plus side panel in Chrome next to a blog draft, showing 27% plagiarism, 9% AI content and the matching passages from example-journal.org
How it works

From draft to report in four steps

  1. 1

    Add it to Chrome

    Install the extension and pin it to your toolbar. Checking works right away as a guest, or sign in to use your account.

  2. 2

    Pick your text

    Click Check on a text box you are writing in, highlight 50+ words on any page, or paste text into the side panel.

  3. 3

    Choose your checks

    Tick AI detection, Plagiarism, or both. You see the word count and what the check will use before you start.

  4. 4

    Review the results

    Scores, matching sources and AI-flagged sentences appear in the side panel, with the full report one click away.

Side panel

Your scores and sources, right beside the page

Click the toolbar icon to open the side panel, paste or bring in your text, and choose AI detection, Plagiarism, or both. Results stay next to the page you are working on, so you can fix a sentence and check again without switching tabs.

  • Plagiarism % with every matching source and the passages that match it
  • AI content % with a plain-language verdict
  • A “Your text” view that marks matches and AI-likely sentences in your own writing
  • Open the full report on the web app when you want more detail
Plagiarism Checker Plus side panel in Chrome next to a blog draft, showing 27% plagiarism, 9% AI content and the matching passages from example-journal.org
Check while you write

A Check button in your text boxes

Writing a forum reply, an email or a discussion post? A small Check · N words button sits in the corner of the box. One click sends that text to the side panel, ready to check before you post it.

  • Appears on text boxes once they hold 50 or more words
  • Works in plain text areas and rich editors such as Gmail
  • Or right-click inside a text box and choose “Check this text box”
  • Hide it on any site with the ×, or turn it off in settings
A forum reply box with the “Check · 82 words” button in its corner, and the side panel ready to check the text for AI detection and plagiarism
Check anything you read

Highlight text, check it instantly

Want to know whether an article, a submission or a snippet you found reads as original? Highlight it. The bar hides itself after a few seconds, so it stays out of your way when you are only selecting text.

  • Select 50+ words — drag, double- or triple-click, Shift + arrows, or copy
  • A bar offers Check plagiarism and Check AI next to your selection
  • Or right-click the selection and choose Check for AI & plagiarism
  • Or press Alt + Shift + P to check the selected text
Highlighted paragraphs on an article with a small bar offering Check plagiarism and Check AI for 117 words, and results with matches underlined in the side panel
AI detection

See which sentences read as AI-written

An overall AI score only tells you so much. The AI sentences tab shows exactly which sentences drove it, so you know what to reread and rewrite in your own voice.

  • Flagged sentences listed most likely first, each with a likelihood
  • A count of how many sentences look AI-generated out of those judged
  • The same sentences shaded in the “Your text” view
The AI sentences tab listing sentences that look AI-generated, most likely first, each with a likelihood such as High 93%
Citation generator

Cite the page you’re reading in one click

Open the Cite tab, or right-click a page and choose Cite this page. The extension reads the citation information the page publishes and formats a reference you can paste straight into your bibliography. Signed in, you can save it to a project on the citation generator and build your reference list as you research.

  • APA 7, MLA 9, Chicago and Harvard
  • Built from the page’s own citation details — title, authors, dates, publisher
  • DOIs looked up automatically when you are signed in
  • Edit any detail, copy with italics intact, and save to a citation project
The Cite tab of the side panel showing an APA 7 citation for a journal article, with MLA 9, Chicago and Harvard tabs, a Copy citation button and Save to a project

Long checks keep running in the background

Close the side panel or move on to another tab — a long plagiarism check keeps going. When it finishes you get a Chrome notification and a ✓ badge on the extension icon.

Your recent checks, one click away

The History tab lists recent checks from your account, plus guest checks made in this browser, so you can reopen a result instead of running the check again.
Privacy

You stay in control

The extension only sends text to Plagiarism Checker Plus when you ask it to — and you decide where its buttons appear.

Text is sent only when you click Check

The extension reads a text box or your selection on your device only to count words. Text leaves your browser when you click a check button, use the right-click menu or press Alt+Shift+P — never before. Password fields are never read.

Hide the buttons on any site

Click the × on the Check button or the highlight bar to hide them on that website. Change your mind later from the settings menu in the side panel.

Or turn them off entirely

In the side panel’s settings menu, switch off “Check button in text boxes” or “Check buttons on selected text”. Right-click checks and the side panel still work.

The extension does not record your browsing history, keystrokes, or activity on pages you do not check. Text you check is used only to produce your results — we never sell it and never use it to train AI models. Read the full details in section 6 of our privacy policy.

No detector is perfect
AI detection gives a likelihood, not proof. It can flag human writing — especially formal or formulaic text — and miss AI text that has been heavily edited. Plagiarism matches show you the source text so you can judge each one yourself. Treat every result as a starting point for review, not a verdict.
Also for Google Docs™

Writing in Google Docs? Use the add-on.

The extension’s in-page buttons are switched off on Google Docs. Our Google Docs add-on checks the whole document or your selection from a sidebar, highlights matched and AI-likely passages right in the document, and inserts citations at your cursor.

See the Google Docs add-on
The Plagiarism Checker Plus sidebar in Google Docs with matched passages highlighted in the document
FAQ

Chrome extension questions

Yes, the extension is free to install. Without an account you get one free check per tool (AI detection and plagiarism) of up to 1,000 words, the same as on our website. A free account gives you a monthly word allowance, and paid plans add more — the side panel shows how many words a check will use and how many you have left before you start. Copying a citation works without an account; saving citations to a project needs you to sign in.

Check your writing anywhere on the web — free to install

AI detection, plagiarism checking and one-click citations in Chrome’s side panel. Start as a guest, or see plans when you need more words.

Coming soon to the Chrome Web StoreTry the web app

Google Docs and Chrome are trademarks of Google LLC. Plagiarism Checker Plus is not affiliated with or endorsed by Google. · Privacy policy · Terms of service