Copyscape vs Crossref Similarity Check

Copyscape checks web pages and newly written human- or AI-generated content for plagiarism and duplicate text found online. Its free checker scans a URL and presents a word-by-word comparison of results, but shows no more than 10 search results and limits scans per website. Premium accepts pasted text as well as PDF and Word uploads for originality checks. Its Batch Search can process up to 10,000 pages in one operation, with each page billed like a regular search. The Premium API can automate plagiarism and AI checks and return results in JSON, XML, or HTML; a WordPress plugin supports checks in a WordPress workflow. Premium users can create a private index of their own content, accessible only through their Copyscape account. Copysentry monitors selected pages daily or weekly and emails alerts when it finds copies. Enterprise can be hosted on-premises or in a private cloud. Copyscape says it uses Google for search and then processes results with proprietary algorithms. It warns that AI detector results may misclassify human or AI text and should not be the sole basis for disciplinary action.

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.