Docs checked API New
Copyscape
Duplicate content search that finds copies of a web page or text elsewhere online.
Plagiarism & Originality Checkers from USD 0.03
The best plagiarism checkers
Similarity engines ranked by corpus, reporting and what they cost per document.
Read this before the list
Plagiarism detection and AI detection answer different questions. A clean similarity report says nothing about whether a model wrote the text.
| # | Tool | Level | Price | Free tier |
|---|---|---|---|---|
| 1 | Copyscape Duplicate content search that finds copies of a web page or text elsewhere online. | Docs checked API | USD 0.03 | - |
| 2 | DupliChecker Free web-based plagiarism checker with paid search-and-word packages and API access. | Docs checked API | USD 9.99 | Yes |
| 3 | Grammarly Plagiarism Checker Plagiarism detection built into Grammarly's writing assistant, included with Pro plans. | Docs checked | USD 12.00 | Yes |
| 4 | iThenticate Originality screening for researchers and publishers checking manuscripts before publication. | Docs checked | USD 125.00 | - |
| 5 | Plagiarism Checker X Desktop plagiarism and text-similarity software sold as a one-time perpetual licence. | Docs checked | USD 39.95 | Yes |
| 6 | Plagiarism Detector Online plagiarism checker with a free tier, paid word packages and a developer API. | Docs checked API | USD 20.00 | 1000 words |
| 7 | Quetext DeepSearch plagiarism checker with AI detection, citation assistant and bulk uploads. | Docs checked API | USD 14.99 | 1000 words |
| 8 | Scribbr Plagiarism Checker Per-document plagiarism check for students, priced by word count rather than subscription. | Docs checked | USD 19.95 | Yes |
| 9 | Turnitin Similarity Similarity checking that compares submissions against student papers, publications and web content. | Established API | Not stated | - |
| 10 | PlagiarismCheck.org Plagiarism and AI detection for individuals and organizations, with LMS add-ons and an API. | Listed API | Not stated | - |
Docs checked API New
DupliChecker
Free web-based plagiarism checker with paid search-and-word packages and API access.
Plagiarism & Originality Checkers from USD 9.99
Docs checked New
Grammarly Plagiarism Checker
Plagiarism detection built into Grammarly's writing assistant, included with Pro plans.
Plagiarism & Originality Checkers from USD 12.00
Docs checked New
iThenticate
Originality screening for researchers and publishers checking manuscripts before publication.
Plagiarism & Originality Checkers from USD 125.00
Docs checked New
Plagiarism Checker X
Desktop plagiarism and text-similarity software sold as a one-time perpetual licence.
Plagiarism & Originality Checkers from USD 39.95
Docs checked API New
Plagiarism Detector
Online plagiarism checker with a free tier, paid word packages and a developer API.
Plagiarism & Originality Checkers from USD 20.00
Docs checked API New
Quetext
DeepSearch plagiarism checker with AI detection, citation assistant and bulk uploads.
Plagiarism & Originality Checkers from USD 14.99
Docs checked New
Scribbr Plagiarism Checker
Per-document plagiarism check for students, priced by word count rather than subscription.
Plagiarism & Originality Checkers from USD 19.95
Established API New
Turnitin Similarity
Similarity checking that compares submissions against student papers, publications and web content.
Plagiarism & Originality Checkers Price on request
Listed API New
PlagiarismCheck.org
Plagiarism and AI detection for individuals and organizations, with LMS add-ons and an API.
Plagiarism & Originality Checkers Price on request