Free Chrome™ extension

AI Detector Extension & Plagiarism Checker for Chrome

Check what you write in any text box, check text you highlight, and cite the page you are reading — all from Chrome’s side panel.

Add to Chrome — it’s free
  • Free to install
  • Works as a guest
  • Text sent only when you click Check
Plagiarism Checker Plus AI detector and plagiarism checker in the Chrome side panel next to a blog draft, showing 27% plagiarism, 9% AI content and the matching passages from example-journal.org
50-second demo

See the AI checker extension in action

A Check button in a text box, a check on highlighted text, results in the side panel and a citation for the page.

How it works

How to check text for AI and plagiarism in Chrome

  1. Add it to Chrome

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

  2. Pick your text

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

  3. Choose your checks

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

  4. Review the results

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

Side panel

Choose your checks, right beside the page

Open the side panel from the toolbar icon, paste or bring in your text, and results stay next to the page you are working on.

  • AI detection, plagiarism, or both at once
  • See the words a check uses before you start
  • Fix a sentence and check again without switching tabs
The extension side panel’s Check tab with text from a forum reply box, AI detection and Plagiarism both ticked, 82 words that will use 164 of 41,800 words left, and a Check text button
Check while you write

A Check button in your text boxes

Writing a forum reply, an email or a discussion post? One click on Check · N words sends that text to the side panel, ready to check before you post.

  • Appears once a text box holds 50+ words
  • Works in plain text areas and editors such as Gmail
  • Or right-click inside the box: “Check this text box”
The Chrome extension’s “Check · 82 words” button in the corner of a forum reply box, with the side panel ready to check the text for AI writing and plagiarism
Check anything you read

Highlight text, check it for AI and plagiarism

Want to know whether an article or a snippet reads as original? Highlight it. The bar hides itself after a few seconds when you are only selecting text.

  • Select 50+ words and a bar offers Check plagiarism and Check AI
  • Or right-click: Check for AI & plagiarism
  • Or press Alt + Shift + P
Highlighted paragraphs on an article with the extension’s 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 score only tells you so much. The AI sentences tab shows which sentences drove it, so you know what to reread and rewrite in your own voice.

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

Cite the page you’re reading

Open the Cite tab, or right-click a page and choose Cite this page. Signed in, save references to a project on the citation generator.

  • APA 7, MLA 9, Chicago and Harvard
  • Built from the page’s own title, authors, dates and publisher
  • DOIs looked up automatically when you are signed in
  • Copy with italics intact, or save to a citation project
The citation generator in the Chrome 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 switch tabs — 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 checking again.
Privacy and permissions

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 ask

Text leaves your browser only when you click a check button, use the right-click menu or press Alt+Shift+P. Password fields are never read.

Why it can read web pages

Chrome asks for access to the sites you visit so the extension can show its buttons, count the words in a text box on your device, read your selection and cite the page.

No tracking, no AI training

It does not record your browsing history, keystrokes or activity on pages you don’t check. Checked text is never sold or used to train AI models.

Hide the buttons on any site

Click the × on the Check button or the highlight bar to hide them on that website. Show them again from the side panel’s settings menu.

Or turn them off everywhere

Untick “Check button in text boxes” or “Check buttons on selected text” in settings. Right-click checks and the side panel keep working.

Sign in and out on your terms

Sign in through our website. Disconnect a browser from the extension connect page at any time; signing out removes the token from your browser.

Full details are in section 6 of our privacy policy.

Also for Google Docs™

Writing in Google Docs? Use the add-on.

The extension’s in-page buttons are off on Google Docs. The add-on checks the whole document or your selection, highlights matches and AI passages in place, and inserts citations.

The Plagiarism Checker Plus sidebar in Google Docs with matched passages highlighted in the document
FAQ

Chrome extension questions

Yes. Plagiarism Checker Plus is a free Chrome extension that checks text for AI writing and plagiarism from Chrome’s side panel. Click Check in a text box, highlight 50 or more words on a page, or paste text into the panel. You get an AI score, the sentences most likely AI-generated, and a plagiarism score with matching sources.

Check your writing anywhere on the web

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

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