Crossref Similarity Check

Crossref Similarity Check is a manuscript-screening service for publishers and editorial teams. It suits organizations that publish DOI-assigned content and want similarity reports within their editorial process. Its large scholarly comparison database and API support are useful, but access depends on Crossref membership and costs scale with use.

Overview

Editors can submit manuscripts through iThenticate or a manuscript system connected by API, then receive an immediate report with a Similarity Score and highlighted matching text. The report helps editors examine overlap; it does not decide whether plagiarism occurred. PDF export provides a shareable record for review.

The service uses Turnitin’s iThenticate software and compares submissions with academic and general web content. Crossref says the database includes more than 78 million full-text scholarly content items. Turnitin’s Content Intake System checks Crossref metadata daily to find participating members’ full-text URLs and index linked content. This broad scholarly reach is valuable for academic publishing, though matching passages still need editorial context.

Key features

• Flexible submission: Editors can use the iThenticate tool directly, while publishers can connect a submission system through the API. The API route is the better fit for teams integrating checks into an existing workflow.
• Member benefits: Members receive read-only access to full text in the comparison database, discounted checking fees, unlimited organizational user accounts, and enhanced text matches in Document Viewer. Unlimited accounts suit larger editorial organizations, while read-only access does not imply broader reuse rights.
• Editorial workflow: An immediate report showing potential matches can help editors triage submissions promptly. Similarity scores and highlights are evidence to assess, not a substitute for editorial judgment.

Pricing

Similarity Check has no free plan. The annual service fee is $40 a year, billed within the annual membership fee invoice and prorated for the remainder of the calendar year when first joining. The fee is 20% of the annual Crossref membership fee, so the amount depends on membership tier.

Per-document checking is free for the first 100 documents each year. Crossref invoices usage annually in January for the previous year. After the first 100, rates are $0.75, $0.65, $0.55, $0.45, $0.30, or $0.25 per document depending on annual volume tier; the published schedule applies to documents up to 25,000 words. Volume discounts help frequent users, but the annual membership-linked fee and per-document charges make costs less attractive for occasional checks. The stated starting price is $40/yr, but the service fee varies with membership tier and checking charges depend on volume.

Participation requires Crossref membership, active publication of DOI-assigned content, and full-text URLs in metadata. Members based in Russia cannot use the service. Those requirements rule it out for independent authors and publishers that do not meet Crossref’s criteria.

Platforms

The service is available on web and through an API. The web route supports direct submission; API access lets publishers connect manuscript systems. Crossref directs users to Turnitin’s service status page for real-time performance updates.

Who it's for

Similarity Check is best for qualifying scholarly publishers that screen manuscripts regularly, especially teams that can use the API, benefit from unlimited organizational accounts, or reach higher-volume checking tiers. It is a poor fit for individual writers, organizations without active DOI publication, or anyone seeking a free checker.

Pros and cons

• Pros
  • More than 78 million full-text scholarly items plus general web content provide a substantial basis for manuscript comparison.
  • Direct submission and API integration accommodate both smaller editorial workflows and connected submission systems.
  • The first 100 documents per year have no per-document charge, and subsequent rates fall by volume tier.
  • Unlimited organizational accounts avoid a per-seat restriction for member teams.
• Cons
  • Crossref membership, DOI-assigned publishing, and metadata requirements exclude many potential users.
  • The annual service fee is tied to membership tier, with additional charges after the first 100 documents.
  • Members based in Russia are excluded.
  • Reports surface matching text but leave interpretation and plagiarism decisions to editors.

Alternatives

For a broader set of options, see Plagiarism Checkers.

Choose Noplag if a freemium tool with web, desktop, self-hosted, or API platforms better suits your workflow: its free plan allows 3 checks per month of up to 2,500 words against public web and Common Crawl.

Dolos is a free, MIT-licensed open-source option with a web app and ZIP uploads limited to 10 MB.

Plagiarism Detector is a freemium alternative with web and Windows access; its free demo allows 10 checks total, covering the first 700 words per document and one document per session.

Choose Copyscape for freemium web, API, or self-hosted access, including limited free URL scans and Copysentry weekly protection at $4.95 a month.

MOSS is a free alternative for non-commercial use, with 100 submissions per day per user.

Originality.ai offers API, extension, and web access; its free Basic plan focuses on AI detection, with 3 scans per day and 2,000 words per scan.

PlagAware is a freemium web and API alternative, with a free plan covering 10 pages per month and up to 30 monitored URLs.

Plagiarism Checker X is a Windows-only freemium option with a free plan that has limited words and daily searches, plus a one-time Professional license.

Verdict

Choose Crossref Similarity Check if you are an eligible scholarly publisher that needs editorial comparison against a substantial academic corpus, particularly when API integration or high-volume checking matters. The main reason to choose it is the combination of scholarly coverage, editorial reports, and member-scale access; look elsewhere if you lack qualifying Crossref membership or need a free, standalone checker.