Students
Check essays, assignments and theses before submission. Fix citations and paraphrasing while there is still time to revise.
Source-aware review
Online Plagiarism Checker
Check essays, theses, research papers, and professional documents for plagiarism before they move forward — with the passages and sources behind every similarity result.
How it helps
See the passages and sources behind a similarity result.
Find likely source matches across web pages and academic sources, with surrounding context you can inspect.
Review highlighted passages and AI-content signals instead of relying on a single percentage.
Download an evidence-rich report for your own revision, a supervisor review, or a publishing workflow.
A clear workflow
From upload to a report you can defend.
- 01
Upload your document
Sign in, make sure you have credits, and add a DOC, DOCX, PDF, TXT or RTF file from your dashboard. One credit covers one complete check.
- 02
We scan the sources
Your document is compared against web pages and academic sources while AI-content signals are analyzed in parallel.
- 03
Review the evidence
Inspect highlighted passages connected to their sources — not just a single percentage — usually within a few minutes.
- 04
Download and revise
Save the evidence-rich report, improve attribution and paraphrasing, and submit or publish with confidence.
Inside the report
More than a similarity score.
Every completed check produces a report you can read, share, or download — built for revision, not just a number.
Check your documentSimilarity percentage with matched passages highlighted directly in your document context.
Source list behind the matches, so you can verify what was found instead of taking a number on trust.
AI-content probability signal with supporting evidence, analyzed alongside similarity in the same check.
Optional highlight generation that pinpoints exactly which parts need attribution or rewriting.
Downloadable report for supervisors, editors, co-authors, or your own records.
Who it serves
Built for careful readers.
Educators & researchers
Review student work and manuscripts with source evidence attached, so feedback and decisions rest on something visible.
Writers & publishers
Screen articles, reports and client content for accidental matches before they reach an editor or go live.
Bring your file as it is.
.doc.docx.pdf.txt.rtf
Files up to 100MB. Your documents stay private — retained for up to 30 days, then automatically deleted, and removable manually at any time.
What a plagiarism checker detects
A plagiarism checker compares your document with existing text and reports the passages that overlap. In PlagCheckr, those overlaps appear as highlighted passages connected to the source that produced the match, so you can see the evidence rather than a single number.
Matching text is not automatically a problem. Quotations, titles, common phrases, reference lists, and assignment wording can all match legitimately. The useful question is whether each match has the attribution it needs.
- Direct matches where wording is close to a source.
- Paraphrases that keep the original structure or phrasing too closely.
- Repeated passages that need a citation or quotation marks.
- Matches that turn out to be correctly cited material after review.
Understand similarity results
The similarity percentage describes how much of the checked document matched sources in that particular check. It is a review signal, not a verdict. A high score with properly cited quotations is a very different situation from a low score with one unattributed paragraph.
Scores also depend on the document: a short essay with a long reference list can show matches from bibliography entries, while a technical paper can repeat standard terminology. Read the highlighted passages before drawing any conclusion.
Review matched sources
Open each highlighted match and look at the surrounding text. Ask three questions: Is the wording copied, paraphrased, or coincidental? Is the source already cited? Would a quotation, a citation, or a genuine rewrite fix the issue?
This is also the fastest way to catch accidental plagiarism — notes that lost their source during drafting, or a paraphrase written too close to the original sentence.
Plagiarism checking for essays, theses, and research papers
Different academic documents fail in different ways, which is why the review step matters more than the score. PlagCheckr runs the same evidence-first check on all of them; the interpretation changes with the document.
- Essays: check quoted passages, paraphrased arguments, and whether every borrowed idea carries a citation.
- Theses and dissertations: expect repeated terminology and a large bibliography — review the body text rather than treating reference matches as findings.
- Research papers: compare the manuscript before submission and confirm that quotations, data descriptions, and prior-work summaries are attributed.
- Professional documents: screen reports and client content for passages reused from earlier drafts or public sources.
Common questions
Plagiarism checking, explained.
Explore PlagCheckr
Compare the tools and resources that support a careful content review.