Verbatim and paraphrase detection
Aligns copied wording and surfaces possible reworded borrowing. Same-topic discussion alone is not proof of copying.
Plagiarism checker built for research papers and theses
PlagLab is ResearchGuru.AI's manuscript similarity checker. Upload a PDF, DOCX or TXT file to compare it with retrievable scholarly literature, including sources discovered through OpenAlex, arXiv, Crossref and Semantic Scholar. Inspect aligned text and source links, citation context, possible reworded borrowing and separate probabilistic AI-text signals.
Free account: 50 tokens every month · no card needed
Exact overlapsupported shared words, counted once in the eligible manuscript body
Reworded leadssource relationships to inspect separately from the exact-text percentage
Source evidenceretrievable literature; coverage and access limitations apply
Separate signalsAI-text analysis is probabilistic, not an authorship verdict
Timings, where shown, are historical observations from October 2026, not a service guarantee. Document size, source access and load affect results. Read the method and limitations for integrity checks.
What it does
Features of the Plagiarism Checker
AI-authorship signal
Shows probabilistic AI-text signals separately from source similarity. A signal does not establish who wrote a passage.
Citation integrity
Shows quotation and citation context so you can distinguish attributed overlap from a passage that needs review.
Scholarly sources
Searches open literature live — OpenAlex, arXiv, Crossref, Semantic Scholar, Wikipedia, Project Gutenberg and the Internet Archive.
Highlighted report
A professional PDF report with similarity and AI passages highlighted in different colours, ready to share with a supervisor.
Private case history
Your reports are filed in your own account's docket, visible only to you.
How it works
From draft to result in 4 steps
- Upload the manuscriptDrop a PDF, DOCX, DOCM or TXT file — up to about 30 MB. Checking starts immediately.
- Choose the depthA standard check covers most papers; the deep and maximum sweeps read more candidate sources in full for a thesis.
- Read the evidenceEvery match links to its source with the overlapping text side by side, so you can judge it rather than trust a number.
- Fix and re-checkRevise, cite or quote the flagged passages — or use the Remediation Lab — then run the check again.
Who it's for
Built for the people who write research
PhD candidatesCheck each thesis chapter before it goes to your supervisor.
ResearchersCatch unintentional overlap before a journal's own check does.
SupervisorsReview a student draft with evidence, not just a percentage.
EditorsScreen submissions for copied and AI-generated passages.
Questions
Frequently asked questions
Is the plagiarism checker free?
Every tool opens on the free plan: a free account gets 50 tokens every month. Longer documents, downloads and some advanced modes need a paid plan — the tool tells you when you reach one.
What similarity percentage is acceptable for a research paper?
There is no universal number. Journals look at what matched: properly quoted and cited text, standard method phrasing and your own references are normal; long uncited passages are not. Read the matches, not just the total.
Does it detect paraphrasing, not just copy-paste?
It can surface reworded source leads, but recall is limited and depends on retrieving the source. Those leads are separate from the exact-text percentage and require human review. See how PlagLab works.
Will my paper be stored?
Your report is kept in your private case history so you can reopen it. Checked manuscripts are also kept in PlagLab's private comparison vault — that is how a later copy of the same text gets caught.
Is this the same as Turnitin or iThenticate?
It is an independent checker that searches open scholarly sources. Publishers and universities may run their own licensed tools as well; checking with PlagLab first helps you fix problems before submission.
Understand the next step
Related research guides
How ResearchGuru.AI checks manuscript similarity and AI text
How PlagLab finds sources, counts exact overlap and separates reworded leads from AI-text signals. Understand coverage, evaluation and report limitations.
Read the guide →How to reduce similarity in a research paper — the right way
Read a similarity report properly and fix what matters: quoting, paraphrasing with citation, method phrasing, self-overlap and reference lists.
Read the guide →How much plagiarism is acceptable in a research paper?
There is no universal safe percentage. What editors actually check in a similarity report, where formal limits exist, and how to read your score.
Read the guide →Related
Tools that pair well with it
AI Content Detector
Check whether text reads AI-written — and see why. Explainable score, per-sentence heatmap, batch files and an exportable report.
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Paraphrasing Tool
Paraphrase academic text in eleven modes and seven tones. Click any sentence for fresh rewrites, keep citations frozen and compare versions side by side.
Learn more →
Citation Generator
Turn a DOI, title, author, ORCID or topic into real, formatted citations in APA, MLA, Chicago or BibTeX — from indexed literature, with links.
Learn more →
Try the Plagiarism Checker now.
Open it in your browser — nothing to install.