Best Plagiarism Detection Software in 2026
Updated
In short: Noplag is ranked #1 of 28 as of 8 October 2026, ahead of Noplag Engine and Dolos. The best-ranked option with a free plan is Noplag Engine. The lowest first paid tier on this page is Copyleaks AI Detector at $1.17/mo.
Plagiarism detection software helps you review writing for material that may have appeared elsewhere. Compare maximum check size and supported languages with the documents you expect to review, and consider whether LMS integrations or a browser extension fit your workflow. AI detection and API access are additional listed capabilities; free-plan availability and paid-from pricing help frame access and cost. Noplag, Noplag Engine, and JPlag are among the entries to compare against your review process.
28 plagiarism detection software ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
14 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 | 6.6 | |
| 2 | Noplag EngineWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | $9.99/mo | 6.6 | |
| 3 | DolosWeb · Windows · Linux · Self-hosted · API | Three bars | — | 3 of 6 | Free | 6.5 | |
| 4 | JPlagWindows · Mac · Linux · Self-hosted · API | Three bars | — | 3 of 6 | Free | 6.5 | |
| 5 | PlagiumWeb · Android · iPhone | Three bars | — | 3 of 6 | Free | 6.5 | |
| 6 | CopyscapeWeb · Self-hosted · API | Two bars | — | 1 of 6 | $4.95/mo | 6.4 | |
| 7 | GPTZeroWeb · API · Extension | Two bars | — | 1 of 6 | $8.33/mo | 6.4 | |
| 8 | MOSSWeb · Linux | Two bars | — | 2 of 6 | Free | 6.4 | |
| 9 | Originality.aiWeb · API · Extension | Two bars | — | 1 of 6 | $12.95/mo | 6.4 | |
| 10 | PangramWeb · API · Extension | Two bars | — | 1 of 6 | $1.67/mo | 6.4 | |
| 11 | PlagiarismaWeb · Windows | Two bars | — | 2 of 6 | Free | 6.4 | |
| 12 | Quetext AI DetectorWeb · API · Extension | Two bars | — | 1 of 6 | $7.99/mo | 6.4 | |
| 13 | SmallSEOTools Plagiarism CheckerWeb · API · Extension | Two bars | — | 1 of 6 | $7.84/mo | 6.4 | |
| 14 | Winston AIWeb · API · Extension | Two bars | — | 1 of 6 | $5/mo | 6.4 | |
| 15 | WINNOWRWeb · Linux · Self-hosted · API | One bar | — | — | 2 of 6 | — | 5.5 |
| 16 | Copyleaks AI DetectorWeb · API · Extension | One bar | — | — | 1 of 6 | $1.17/mo | 5.4 |
| 17 | DupliCheckerWeb · API | One bar | — | — | 1 of 6 | $9.99/mo | 5.4 |
| 18 | Plag.aiWeb | One bar | — | — | 1 of 6 | €14.95/mo | 5.4 |
| 19 | PlagiarismCheck.orgWeb · API · Extension | One bar | — | — | 1 of 6 | — | 5.4 |
| 20 | PlagiarismDetector.netWeb · API · Extension | One bar | — | — | 1 of 6 | $9.99/mo | 5.4 |
| 21 | Scribbr Plagiarism CheckerWeb | One bar | — | — | 1 of 6 | — | 5.4 |
| 22 | Turnitin OriginalityWeb | One bar | — | — | 1 of 6 | — | 5.4 |
| 23 | CodeleaksWeb · Self-hosted · API | One bar | — | — | 1 of 6 | — | 5.3 |
| 24 | CodequiryWeb · Windows · Mac · Linux · API | Two bars | — | — | 4 of 6 | €25.76/mo | 5.2 |
| 25 | PlagiusWeb · Windows · Mac | Two bars | — | — | 3 of 6 | $4.90/mo | 5.2 |
Compare all 25 in a table
| # | App | Score | Free plan | From | Free plan | Paid from | AI detection | LMS integrations |
|---|---|---|---|---|---|---|---|---|
| 1 | Noplag | 6.6 | Free plan | $9.99/mo | Yes | — | — | — |
| 2 | Noplag Engine | 6.6 | Free plan | $9.99/mo | Yes | — | No | Yes |
| 3 | Dolos | 6.5 | Free plan | Free | Yes | — | — | — |
| 4 | JPlag | 6.5 | Free plan | Free | Yes | — | No | No |
| 5 | Plagium | 6.5 | Free plan | Free | Yes | — | — | Yes |
| 6 | Copyscape | 6.4 | Free plan | $4.95/mo | Yes | — | — | — |
| 7 | GPTZero | 6.4 | Free plan | $8.33/mo | Yes | — | — | — |
| 8 | MOSS | 6.4 | Free plan | Free | Yes | — | — | — |
| 9 | Originality.ai | 6.4 | Free plan | $12.95/mo | Yes | — | — | — |
| 10 | Pangram | 6.4 | Free plan | $1.67/mo | Yes | — | — | — |
| 11 | Plagiarisma | 6.4 | Free plan | Free | Yes | — | — | Yes |
| 12 | Quetext AI Detector | 6.4 | Free plan | $7.99/mo | Yes | — | — | — |
| 13 | SmallSEOTools Plagiarism Checker | 6.4 | Free plan | $7.84/mo | Yes | — | — | — |
| 14 | Winston AI | 6.4 | Free plan | $5/mo | No | — | — | — |
| 15 | WINNOWR | 5.5 | No | — | Yes | — | — | — |
| 16 | Copyleaks AI Detector | 5.4 | No | $1.17/mo | — | — | — | — |
| 17 | DupliChecker | 5.4 | No | $9.99/mo | Yes | — | — | — |
| 18 | Plag.ai | 5.4 | No | €14.95/mo | Yes | — | Yes | — |
| 19 | PlagiarismCheck.org | 5.4 | No | — | Yes | — | — | — |
| 20 | PlagiarismDetector.net | 5.4 | No | $9.99/mo | Yes | — | — | Yes |
| 21 | Scribbr Plagiarism Checker | 5.4 | No | — | Yes | — | — | — |
| 22 | Turnitin Originality | 5.4 | No | — | No | — | Yes | Yes |
| 23 | Codeleaks | 5.3 | No | — | — | — | No | — |
| 24 | Codequiry | 5.2 | No | €25.76/mo | No | — | Yes | Yes |
| 25 | Plagius | 5.2 | No | $4.90/mo | No | — | — | No |
Is your app on this list?
Numbered spots on this list can be sponsored, and a sponsored row is labelled as paid.
Questions about this list
Which plagiarism detection software is ranked first on Freedom251?
Noplag is ranked #1 of 28 with a score of 6.6. Noplag Engine is second and Dolos third.
How many of these have a free plan?
14 of the 25 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, Copyleaks AI Detector has the lowest first paid tier we found: $1.17/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.