Free plagiarism checker with AI detection

Check your text against billions of web pages and academic sources. See every match sentence by sentence, and which sentences read as AI-written.

PlagiarismAI detector
0 / 1,000 words·0 chars
Scan options
What you get
  • Billions of web pages, journals & sources
  • Sentence-by-sentence similarity report
  • Auto-detects your language
  • No signup needed for your first scan
  • First check free, no sign-up
  • AI detection included
  • Never used to train AI

Check your writing wherever you work

Web app

Paste, upload or bulk check files, with every report saved to folders.

Open the app

Chrome extension

Check any text box or selection on the web from Chrome’s side panel.

Chrome extension

Google Docs add-on

Check the whole document and see matches highlighted in place.

Docs add-on

API

Send text from your own app and get scores and sources as JSON.

API docs
The report

Every match, sentence by sentence

Colour-coded sources, the original text beside yours, and the tools to fix it — all in one report.

Colour-coded, sentence by sentence

Every matched sentence is underlined in the colour of its source, so overlaps are obvious at a glance.

Essay with each matched sentence underlined in the colour of its source
16 source types to cite

Auto-fill from a URL, DOI or ISBN, or add a source by hand.

Citation generator: auto-fill from URL, DOI or ISBN, or pick one of 16 source types
See the source. Cite it.

Open any match to read the source text, compare side by side, or cite it in one click.

Matched source text with the copied words in red, and Compare side by side and Cite buttons
Remarks on any sentence

Select text to leave feedback, reply, and resolve — like comments in a doc.

A remark on a highlighted sentence, with Resolve and Reply
Folders for every class

Keep reports organised by course, client or project.

Folders: All reports, History essays and Research papers
Share, export and rescan

Send a secure link, download a PDF, adjust text size, or edit and rescan without leaving the report.

Report toolbar: Find, text size, Display, Review and Edit, Share, PDF and Rescan
AI detection

Plagiarism and AI in one report

Run both checks on the same text. You see what matches other sources and what reads as machine-written, without pasting it into a second tool.

  • An AI score for the whole text
  • A likelihood for every sentence
  • Highlighted right in your document
AI detection report: AI-likely sentences highlighted in the essay, a 44% AI score and a confidence for each sentence
Sources

Open any match, read the source, cite it

Click a highlighted sentence to see exactly what it matched. If the source should be credited, add the citation in one click instead of hunting for the details.

  • Copied words shown in red
  • Compare side by side
  • Cite in APA, MLA, Chicago or Harvard
Match detail: the matched source text with the copied words in red, and buttons to compare side by side or cite the source
For schools and universities

Your archive, your domain, every class

Admins, managers, teachers and students work in one workspace. New submissions are checked against your own past papers as well as the web.

  • Private repository of past papers
  • Bulk and automatic scanning
  • Login page on your own domain
Plagiarism panel listing each matched passage with its source and percentage
Who it’s for

Built for how you write and review

Check your essay before you hand it in, fix what needs a citation, and submit with confidence.

  • One free check without an account
  • Cite any matched source in APA, MLA or Chicago
  • See which sentences read as AI-written
Plagiarism score of 23%: 3 matches from 2 sources
How it works

From paste to full report in three steps

  1. Paste or upload

    Paste text or upload a Word, PDF or text file. Your first check needs no account.

  2. We scan it

    Your text is compared with billions of web pages and academic sources, and checked for AI writing.

  3. Review and fix

    Open each match, read the source, then cite it, quote it or rewrite it — and rescan.

Watch the 2-minute tour: plagiarism, AI detection, citations, Chrome, Google Docs and more.
FAQ

Plagiarism checker questions

Yes. Your first plagiarism check and first AI check are free without an account, up to 1,000 words each. A free account gives you 3,000 words every month. Paid plans add longer documents, bulk upload, folders and API access.

Check your first document free

No account needed for your first plagiarism and AI check.