Direct comparison
Crossref Similarity Check vs Turnitin
They share the same iThenticate engine, not separate technology. Compare access, licensing, corpus, and which applies to journals vs universities.
Side-by-side comparison
| Dimension | Crossref Similarity Check | Turnitin |
|---|---|---|
| What it is | A Crossref member service providing discounted, customized iThenticate access | Turnitin, LLC's flagship education-market plagiarism/AI-writing detection product |
| Underlying engine | iThenticate (Turnitin, LLC) | Its own matching engine; also the basis of iThenticate |
| Owning company | N/A — Crossref administers access; Turnitin, LLC supplies the engine | Turnitin, LLC (formerly iParadigms; owned by Advance Publications since 2019) |
| Who can access it | Crossref members registering DOIs with full-text URLs | Any institution (mainly schools, colleges, universities) via direct license |
| Primary market | Journals and scholarly publishers | Secondary/higher education — student coursework, theses |
| Comparison corpus | Scholarly + web content, expanded by member-contributed full text via Content Intake System | Education-weighted: student submissions, web content, institutional repositories |
| Typical integration point | Manuscript submission systems (e.g. Editorial Manager, ScholarOne, OJS) | Learning management systems (Canvas, Blackboard, Moodle) |
| Pricing model | Annual fee (~20% of Crossref membership fee) + per-document fees, first 100 documents/year free | Direct institutional license, not tied to Crossref membership |
| Reciprocal indexing | Yes — members' published content feeds the shared iThenticate database | No equivalent publisher-contribution requirement |
| Similarity score = plagiarism finding? | No — requires human editorial review of flagged matches | No — requires human review; same caveat applies |
Common questions
FAQ
Is Crossref Similarity Check the same software as Turnitin?+
Not the same product, but the same underlying engine. Similarity Check is a Crossref service giving members discounted access to iThenticate, and iThenticate is built and owned by Turnitin, LLC. A document run through either service is compared using the same core text-matching technology.
Did Turnitin acquire iThenticate in 2019?+
No — this is a common misreading. Turnitin, LLC (as iParadigms) has owned iThenticate since launching it in 2004. In 2019, Advance Publications acquired the entire Turnitin, LLC company — Turnitin and iThenticate together — for a reported ~$1.75 billion. Nothing changed in the Turnitin/iThenticate relationship itself that year.
Can a university use Crossref Similarity Check to check student theses?+
No. Crossref membership is for organizations registering DOIs for published scholarly content, not academic institutions screening coursework. Universities checking student work use Turnitin directly (or license iThenticate separately for research-integrity purposes outside the journal-publishing context).
Does a high similarity score mean a manuscript was plagiarized?+
No, in either system. Quoted material, standard methods language, and common phrasing all raise a raw similarity percentage without indicating misconduct. COPE guidance treats the similarity report as a screening aid that a human editor must interpret, not an automatic verdict.
