Noplag vs Viper
Noplag
noplag.comViper
scanmyessay.comSide by side
| Figure | Noplag | Viper |
|---|---|---|
| Price from | $9.99/mo | — |
| Free plan | Yes | — |
| Free trial | Yes | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | — |
| API | Yes | — |
| Self-hosted | Yes | — |
| Plans published | 4 | 7 |
| Spec score · Plagiarism Checkers | 9.2 (#3) | 6.9 (#28) |
| Spec score · AI Plagiarism Checkers | 9.2 (#3) | 6.9 (#23) |
| Headquarters | San Francisco, United States | Fujairah, United Arab Emirates |
| Reports | Reports link each match to its source and show a similarity score and exact overlapping text, with PDF export. | Viper provides reports with highlighted matches, source URLs and scores, and downloadable PDF reports. |
| Sources | Its comparison sources include the open web, Common Crawl, Wikipedia, academic indexes, the Noplag Database, and users’ own folders. | Viper says it checks against 16,000+ open-access journals, 60 trillion websites and search engines, 1M+ optional internal documents, and 20+ code repositories. |
| Support | Free includes community Discord support, Pro includes email support, and Premium includes priority support with a 12-hour response target. | Viper offers support through LiveChat and email for paid scans. |
Plans
Viper
- Small£5, paid once
- Starter£9, paid once
- Standard£14.95, paid once
- Professional£25.95, paid once
- Advanced£34.95, paid once
- Premium£69.95, paid once
- Ultimate£119.95, paid once
In their own words
Noplag
Noplag is an open-source plagiarism checker with a hosted cloud service and an engine released under Apache 2.0. Its current matching uses winnowing fingerprints and live-web comparison to find verbatim and near-verbatim copying; it does not detect paraphrase. Sources include the open web, Common Crawl, Wikipedia, academic indexes, the Noplag Database and users’ own folders. Submit DOCX, PDF, TXT, ODT or RTF files, paste text or provide a URL. Reports link matches to their sources, display similarity scores and exact overlapping text, and can be exported as PDFs. Detection is calibrated at launch for English, Spanish, Portuguese, Polish and Ukrainian. AI-content detection is marked as coming soon and intended as a separate signal. The free plan allows three checks per month, up to 2,500 words per check, with community Discord support. Pro costs $9.99 a month and includes 50 monthly checks, up to 25,000 words per check, database and academic-index matching, REST API and webhooks, and email support. A 14-day trial is listed.