Crossref Similarity Check vs Originality.ai

Crossref Similarity Check is a paid plagiarism-screening service for Crossref members. It compares submitted manuscripts with academic publications and general web content, using Turnitin’s iThenticate software. Reports provide a Similarity Score and highlight matching passages for editorial review. Crossref says the comparison database contains over 78 million full-text scholarly content items. Editors can submit manuscripts in iThenticate or through a manuscript system using the API, then receive an immediate report describing potential matches and overlap. Membership includes read-only database access, discounted checking fees, unlimited organizational users, and enhanced text matches in Document Viewer. Participation requires Crossref membership, active publication of DOI-assigned content, and full-text URLs in metadata. The annual service fee is $40 a year, representing 20% of the membership fee. Per-document checking is free for the first 100 documents yearly, then volume-tier charges apply to documents up to 25,000 words.

Originality.ai provides tools for checking AI-generated text, plagiarism, facts, readability, grammar, spelling and content quality. Its free Basic plan costs $0.00 per free and provides three AI scans per day, with up to 2,000 words per scan. The AI detector offers configurable allowances of 0%, 5%, 15%, 25% or 40%. A website scanner can crawl a site, identify pages likely to contain AI-generated content and run scheduled scans. The browser extension scans Google Docs, web pages or selected text, and includes writing replay, typing behavior insights and shareable reports. A REST-based API submits text for AI and plagiarism scans and returns detailed results; the maker says AI detection supports 30 languages. API AI scans require at least 50 words, and the help page says accuracy decreases below 100 words. Originality.ai describes detection results as probabilistic estimates that may produce false positives or false negatives, not conclusive proof. Pro costs $12.95 per month billed yearly, with a monthly option at $14.95 per month. The service is available through web, API and extension.