Check your paper's AI percentage and plagiarism before you submit
PaperCheck scores your research paper, thesis or project report sentence by sentence, shows exactly which lines read as AI-written, and finds copied text from the papers you cite. 5 free checks a month, up to 20,000 words each.
- Your whole paper, not a few hundred words: upload the Word or PDF file you will submit.
- A Turnitin-style AI score, plus a second score for newer AI like Claude and GPT-5.
- Every flagged line, why, and how to fix it, not just one number.
- Plagiarism in the same report, against the papers you cite.
Your paper is deleted as soon as the check finishes.
How it works
1. Upload
Drop a PDF or Word file, or paste your text. We show the word count first, so you know the cost before anything is checked.
2. Check
Every sentence is scored for AI-like writing, and your text is compared with the arXiv papers you cite. The AI result comes first; long papers take a few minutes and are emailed to you.
3. Fix
Each flagged sentence comes with the reason and what to change. Edit it yourself, or copy a paragraph's notes into ChatGPT, Claude or Gemini.
What your report looks like
Chapter 5 explains the implementation, training procedure, baselines and evaluation protocol. The model was trained for 40 epochs on the full dataset, with the learning rate halved after epoch 25. Chapter 6 reports and discusses the results, including significance tests and ablations.
- Reads generic: about the same length as the sentences around it, and no number or result. Name what is specific to your work.
Illustrative example. Each highlighted sentence comes with notes like the one above.
AI checker and plagiarism checker in one
AI percentage, sentence by sentence
Your text is scored in 250-word chunks, the way Turnitin does, for a Turnitin-style AI score, and every flagged sentence is marked in your paper.
Plagiarism against real papers
Your text is compared with the full text of the papers you cite on arXiv, and with related arXiv papers found from your key terms. Copied phrases are shown with their source.
Built for academic writing
Only prose is checked, from the abstract to the references. Tables, captions, equations and the reference list are left out, as in Turnitin.
How this is different from free AI checkers
Most free AI checkers take a few hundred words of pasted text and give you one number. That is not much help when you have a 40-page report due.
| Typical free AI checker | PaperCheck | |
|---|---|---|
| How much text | A few hundred to a few thousand words | The whole paper, up to 20,000 words per free check |
| Files | Paste text only | Word and PDF, read the way Turnitin reads them |
| What you get | One overall percentage | Every flagged line, why it was flagged, and how to fix it |
| Score | Its own scale | A Turnitin-style AI score, judged in 250-word chunks like Turnitin |
| Newer AI models | Often miss Claude and GPT-5 writing | A second score trained on Claude, GPT and Gemini text |
| Plagiarism | Not included, or paid extra | Checked against the papers you cite, in the same report |
| Fixing it | You are on your own | A fix report you can paste into ChatGPT, Claude or Gemini |
Only the running text is checked: the title page, declaration, tables, lists and references are skipped, as in Turnitin.
Free limits
| How you use it | Free words |
|---|---|
| On this website, after signing in with Google | 5 checks a month, up to 20,000 words each |
| From your own AI assistant (ChatGPT, Claude, Gemini, Cursor) | the same 5 checks (shared with the website) |
Use PaperCheck from ChatGPT, Claude or Gemini
Add PaperCheck to your AI assistant as a connector (MCP) with one link. Then just say "check my paper": your assistant runs the AI and plagiarism checks, sees exactly which sentences are flagged, rewrites only those, and checks again.
Connector link: https://paper-check.me/mcp. Get your personal key on the check page.
Frequently asked questions
Is PaperCheck the same as Turnitin?
No. PaperCheck is an independent tool and is not affiliated with Turnitin. It estimates the AI percentage with open AI-text detectors, scored sentence by sentence the way Turnitin reports the share of flagged words. Use it as a pre-submission check, not a guarantee.
How is the AI percentage calculated?
The prose from the abstract to the references is split into sentences. Each sentence is scored with the two sentences before and after it. A sentence counts as flagged when the detector's score is above 50%, and the AI percentage is the share of words in flagged sentences.
What does the plagiarism check compare against?
The full text of the papers you cite that are on arXiv, plus related arXiv papers found by searching with your key terms. It reports copied phrases of eight or more words with their source. It does not search the whole web.
Is my paper stored or used for training?
No. Your paper is deleted as soon as the check finishes and is never used to train anything. Only the scores and flagged snippets are kept for your report.
How do I lower my AI percentage?
Rewrite the highlighted sentences: vary sentence length, use the specific details of your own work instead of general phrases, and cut stock words such as "furthermore", "crucial" or "leverage". Keep every number, citation and technical term unchanged.