Free Plagiarism Checker — Catch Accidental Matches
Paste your draft and we'll flag phrases that match anything on the open web — with source URLs. Catches what your spellchecker misses, before Turnitin sees it.
What our scanner actually checks
A real-time index of the open web. Same coverage Turnitin and Copyscape use — without the upload, the wait, or the bill.
Open-web index
8B+ pages from Google's crawlable index, refreshed weekly. Catches anything published publicly.
4–12 word phrases
Sweet spot for catching real lifts. Shorter = false positives; longer = misses paraphrased copies.
Source URL on every match
You see exactly where each flagged phrase came from. No mystery "similar text found" warnings.
Weighted risk score
Long, unique phrase matches count more than common idioms. Reflects actual integrity risk.
From draft to original in 4 steps
Most accidental plagiarism comes from one of two sources: forgotten quote attributions, or AI tools regurgitating training data. This loop catches both.
Scan
Paste your draft. Get matches in 5-10 seconds with source URLs.
Review
Each flagged phrase shows the source. Decide: cite, rewrite, or leave.
Re-scan
Run the cleaned-up version back through. Confirm risk under 20%.
How we compare
Same coverage of the public web — without the subscription tax or institutional gatekeeping.
| Feature | TextHumanizer | Turnitin | Copyscape | Quetext |
|---|---|---|---|---|
| Free tier | 100 scans/mo | Institution only | Paid only | 500 words |
| Open-web coverage | ✓ 8B+ pages | ✓ | ✓ | ✓ |
| Source URLs | ✓ Direct links | ✓ | ✓ | Limited |
| Per-phrase % match | ✓ | Aggregate only | ✓ | Partial |
| No sign-up | ✓ | Required | Required | Required |
| Built-in humanizer + detector | ✓ One workspace | — | — | — |
| Stores your text | Never | Submitted to corpus | Yes | Yes |
Three workflows where this saves the day
Pre-Turnitin self-check
Run your essay before submitting. Catch the paragraph you accidentally lifted from a Wikipedia tab open last week — before your professor does.
Verify AI-assisted drafts
LLMs sometimes regurgitate training data verbatim. Always scan AI-assisted drafts before publishing — Google penalizes duplicate content.
Verify freelance deliverables
Before paying out, scan the delivered work. Match rate above 20% means you're paying for something the freelancer didn't actually write.
How our plagiarism checker works
Our plagiarism scanner indexes phrases (4-12 words long) from your text and queries them against the open web in real time. Each match returns a similarity score and source URL. The overall risk score weights the number of matches by their length and uniqueness.
Unlike subscription-only checkers, we don't require you to upload a document or sign up. Paste your text, get a result in 5-10 seconds.
What's covered: anything Google has crawled — blog posts, news articles, Wikipedia, government docs, public PDFs, Reddit posts, GitHub README files, academic preprints. What's not covered: private databases (Turnitin's student-submission corpus, paywalled journals via JSTOR/IEEE). For pure open-web matches, our coverage is at parity with paid tools.
Plagiarism + humanization — combined workflow
The complete writing workflow we recommend, especially for AI-assisted drafts:
- Draft with AI assistance (any model)
- Humanize the draft to remove AI signatures
- Detect remaining AI-like passages
- Run the result through this plagiarism checker
- Cite or rewrite any flagged matches
- Submit confidently
The humanizer step is the one most users skip — but it's what catches the regurgitated-training-data problem. AI models sometimes reproduce passages verbatim from their training data; humanizing breaks that pattern before the plagiarism checker even sees it.
Three kinds of plagiarism, one scan
Most "checkers" only catch one of these. Ours catches all three in a single pass:
Direct copy — verbatim phrases lifted from a source. Easiest to spot; the bar most teachers care about.
Mosaic / patchwork — when paragraphs from multiple sources are stitched together with minor edits between them. Common in rushed work. Our overlapping-window matcher catches segments as short as 12 consecutive words.
Self-plagiarism — reusing your own previously published work without attribution. Increasingly flagged by academic policies. Catch it before your professor or editor does.
Paraphrasing (true rewording with new sentence structure) is generally not plagiarism if the underlying idea is properly cited. We don't flag legitimate paraphrasing — that's what the AI humanizer is for, by design.
What this checker doesn't cover (and how to handle it)
Honest about the limits, because the alternative is bad surprises in the wrong places:
Private databases (Turnitin's corpus, paywalled journals). Our index is the open web. If you're submitting work that gets run through Turnitin, treat our scan as a strong pre-screen — anything we flag, Turnitin will too — but Turnitin will also flag matches against private student-submission archives that we can't see.
PDF or DOCX files. The paste box is text-only. To scan a file, copy-paste its contents (CMD/CTRL+A → CMD/CTRL+C → paste). File uploads with auto-extraction are on the Pro plan inside the workspace.
Multilingual scanning. Currently English-only. French, Spanish, and German support is on the late-2026 roadmap.
How to read your match results
Each flagged phrase shows three things: the matching text, the source URL, and a percentage. Here's what the colors mean and what to actually do:
- Green (under 50%): partial overlap, often coincidental. Common idioms, technical jargon, or short phrases that appear naturally in many places. Usually safe to leave — but quick to rewrite if you want a clean scan.
- Amber (50-79%): meaningful overlap. Either cite the source explicitly, or rewrite the sentence structure so it's clearly your phrasing.
- Red (80%+): direct lift or near-direct lift. Cite the source and use quotation marks for direct quotes, or rewrite from scratch. Don't ship without one of these.
The overall risk score weights these by length and uniqueness — five short common-phrase matches at 60% are less risky than one long unique-phrase match at 70%. Trust the per-match colors more than the aggregate when reviewing.
Frequently asked questions
Run all your text through TextHumanizer.
Humanize · detect · plagiarism scan · grammar check — all in one workspace. 100 free uses/month, no credit card.