Best Plagiarism Checkers in 2026
Updated
In short: Noplag is ranked #1 of 31 as of 4 October 2026, ahead of Originality.ai and PlagAware. The best-ranked option with a free plan is Originality.ai. The lowest first paid tier on this page is PrePostSEO Plagiarism Checker at $0.35/mo.
Plagiarism checkers vary in the material they match and the ways they deliver results. This 2026 ranking compares web and academic source matching, supported languages, and word limits, alongside report export formats. If the checker needs to fit into an existing workflow, review LMS integration and API access. Free-plan availability and “Paid from” also show how access and published starting prices differ. PlagiarismCheck.org, PlagiarismSearch, and Noplag are among the first entries shown. Compare the source coverage and reporting features against the writing you need to review.
31 plagiarism checkers ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
6 of the 25 here have a free tier you can use, 0 have open-source code on record, and 0 have full bars: free, open, on most of your devices and documented.
| # | App | Signal | Free tier | Open code | Devices | From | Score |
|---|---|---|---|---|---|---|---|
| 1 | NoplagWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | $9.99/mo | 6.7 | |
| 2 | Originality.aiWeb · API · Extension | Two bars | — | 1 of 6 | $12.95/mo | 6.4 | |
| 3 | PlagAwareWeb · API | Two bars | — | 1 of 6 | €2.99/mo | 6.4 | |
| 4 | PlagiarismaWeb · Windows | Two bars | — | 2 of 6 | Free | 6.4 | |
| 5 | Quetext AI DetectorWeb · API · Extension | Two bars | — | 1 of 6 | $7.99/mo | 6.4 | |
| 6 | SmallSEOTools Plagiarism CheckerWeb · API · Extension | Two bars | — | 1 of 6 | $7.84/mo | 6.4 | |
| 7 | PrePostSEO Plagiarism CheckerWeb · Windows · Mac · Android · iPhone · API | Two bars | — | — | 5 of 6 | $0.35/mo | 5.8 |
| 8 | Smodin Plagiarism CheckerWeb · Android · iPhone · API · Extension | Two bars | — | — | 3 of 6 | $10/mo | 5.6 |
| 9 | DupliCheckerWeb · API | One bar | — | — | 1 of 6 | $9.99/mo | 5.4 |
| 10 | PlagiarismCheck.orgWeb · API · Extension | One bar | — | — | 1 of 6 | — | 5.4 |
| 11 | PlagiarismSearchWeb · API · Extension | One bar | — | — | 1 of 6 | $27.95/mo | 5.4 |
| 12 | ViperWeb | One bar | — | — | 1 of 6 | — | 5.4 |
| 13 | Copyleaks AI DetectorWeb | One bar | — | — | 1 of 6 | — | 5.3 |
| 14 | DolosWeb · Windows · Linux | One bar | — | — | 3 of 6 | — | 5.3 |
| 15 | MOSSWeb · Linux | No signal | — | — | 2 of 6 | — | 5.3 |
| 16 | PlagWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 17 | Plagiarism Checker XWindows | No signal | — | — | 1 of 6 | — | 5.2 |
| 18 | Plagiarism DetectorWeb · Windows | No signal | — | — | 2 of 6 | — | 5.2 |
| 19 | PlagiusWeb · Windows · Mac | Two bars | — | — | 3 of 6 | $0.41/mo | 5.2 |
| 20 | PlagrammeWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 21 | Red PaperWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 22 | Scribbr Plagiarism CheckerWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 23 | CopyscapeWeb | No signal | — | — | 1 of 6 | — | 5.1 |
| 24 | JPlagNo platforms listed | No signal | — | — | 0 of 6 | — | 5.1 |
| 25 | Compilatio AI DetectorWeb | No signal | — | — | 1 of 6 | — | 4.8 |
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which plagiarism checker is ranked first on Freedom251?
Noplag is ranked #1 of 31 with a score of 6.7. Originality.ai is second and PlagAware third.
How many of these have a free plan?
6 of the 25 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, PrePostSEO Plagiarism Checker has the lowest first paid tier we found: $0.35/mo.
How is this list ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation. Paid placements never change a rank.