Noplag
The plagiarism checker you can audit
Noplag is an open-source plagiarism checker that provides source-linked reports showing matched passages, similarity scores, and source URLs. It compares documents against a five-tier corpus including the live web, Common Crawl, Wikipedia, academic papers, and the Noplag Database. The detection engine is Apache 2.0 licensed and can be self-hosted or audited. It also offers AI-content detection (coming soon), a developer API, and LMS integrations.
12 alternatives to Noplag
Ranked by how well each tool replaces Noplag: shared features, audience, price and popularity.
Plagiarism checker and duplicate content detection software.
Covers 1 of 15 key features.
Free plan63 out of 100 matchContact salesPlagiarism detector that checks text originality, verifies authorship, and detects AI‑in‑w
Covers 3 of 15 key features.
63 out of 100 matchContact salesFree online plagiarism checker that scans web sources, academic papers and books for text,
Covers 1 of 15 key features.
Free plan61 out of 100 matchContact sales- 61 out of 100 match$39.95/mo
- 58 out of 100 match$9/mo
AI content detector that checks text for AI-generated writing and writing quality (the tag
Covers 2 of 15 key features.
Free plan57 out of 100 matchContact salesOnline plagiarism and AI-generated content detection for documents.
Covers 0 of 15 key features.
56 out of 100 matchUsage-basedDetect AI content, humanize AI-generated writing, and check images, voice, video and PDFs.
Covers 3 of 15 key features and starts cheaper.
Free plan55 out of 100 match$5/mo- 55 out of 100 match$9.95/mo
- 55 out of 100 matchContact sales
Free AI Detector & ChatGPT Checker | 99% Accurate
Covers 3 of 15 key features and starts cheaper.
Free plan54 out of 100 match$0.42/mo- 53 out of 100 match$2.99/mo