If my journal requires iThenticate, do I still need Noplag?

Different parts of the pipeline. iThenticate is what your journal will run on the manuscript at submission — that's their decision, not yours, and you can't substitute. Noplag is what you run before that submission — on early drafts, on dissertation chapters, on grant proposals, on the version your co-author sent back. Flat-rate makes the iterative self-check affordable in a way per-credit doesn't.

What's the difference vs Crossref Similarity Check?

Crossref Similarity Check is iThenticate access bundled into Crossref membership — same product, member-discounted access. If your journal is a Crossref member, your editor likely uses CSC. Noplag isn't part of Crossref; we run an independent corpus (OpenAlex + CORE + arXiv + PMC + web). Different content base, different pricing model, different audience.

What about ProQuest dissertations? You don't have those?

Correct — iThenticate's edge here is real. ProQuest's dissertation + thesis database is proprietary, paid, and not in OpenAlex/CORE. For PhD students whose dissertation needs cross-checking against prior US dissertations specifically, iThenticate has the dataset we don't. We cover ~700M open-access scholarly works; ProQuest's ~5M dissertations isn't in that set.

Does Noplag integrate with ScholarOne or Editorial Manager?

Not natively. iThenticate's deep integration with the manuscript-tracking systems (ScholarOne, Editorial Manager) is the result of 15+ years of publisher partnerships under Turnitin's umbrella. We have a REST API + webhooks for custom integration, which is the right shape for self-hosted publisher platforms (OJS / PKP) but won't slot in seamlessly to closed editorial systems.

How is the AI-content detection different?

iThenticate's AI detection is a recent add-on and the methodology isn't published; Noplag's AI detection is coming soon, built on Binoculars (Hans et al. 2024, open paper, reproducible) with per-language calibration and a documented ESL-bias adjustment. It will report AI-likelihood as a signal with per-sentence transparency, not a verdict. Neither tool is perfect — but ours is auditable.

Can I self-host Noplag for sensitive primary-source research?

Yes — the detection engine is Apache 2.0, runs in Docker, no phone-home. Enterprise customers get the cloud corpus as an indexable bundle. iThenticate is SaaS-only with no self-host option, which is a blocker for some IRB-restricted research.

Will iThenticate's 894M article database catch things Noplag misses?

On paywalled subscription content from their 1,500 publisher partners — yes, sometimes. iThenticate has subscription-content licenses we don't. On the open-access universe (the vast majority of recent research, especially post-Plan S), the OpenAlex + CORE + arXiv coverage runs ahead or even. The gap matters most for older journal content behind paywalls; less for the past decade.

AN HONEST COMPARISON

Noplag vs iThenticate

Side-by-side from the team that built one of them. iThenticate is the journal-publisher pre-submission standard. Noplag is the open-source alternative for authors, smaller publishers, and self-hosted research setups. We'll be specific about where iThenticate is genuinely better.

noplagOpen-source, since 2014OUR SIDE

iThenticateJournal-publisher, since 2004THE JOURNAL STANDARD

THE QUICK VERDICT

Choose Noplag if

You check many manuscripts per month — flat-rate beats $125-per-document credit pricing fast
You're an author or smaller publisher who isn't a Crossref Similarity Check member
Your IRB / procurement requires reviewing the algorithm before signing — Apache 2.0 is reviewable, iThenticate is closed
Your discipline handles sensitive research that can't leave your network — self-host on Docker
You need an API to embed plagiarism + AI detection in a research-platform product
You need AI-content detection with documented ESL-bias methodology

Choose iThenticate if

Your target journal/publisher already requires iThenticate (Elsevier, Springer, Wiley, IEEE pre-submission workflows)
You're already a Crossref Similarity Check member journal with discounted unlimited access
ProQuest dissertation + thesis database is critical for your discipline (Noplag has OpenAlex + CORE; not ProQuest)
Your editorial workflow runs in ScholarOne Manuscripts or Editorial Manager — iThenticate is natively embedded
You check 2–5 manuscripts per year — per-document credits ($100–$125) beat a monthly subscription
You need iThenticate v2's red-flag hidden-text detection (white-text-on-white attempts to game the checker)

FEATURE COMPARISON

The actual differences, line by line.

ACCESS & CONTRACTS

Individual access

NOPLAGYes — sign up in 30 seconds

ITHENTICATEYes — direct or via Crossref member journal

Pricing model

NOPLAGFlat-rate · $0 / $23 / $79 / Custom

ITHENTICATEPer-document credits · $100–$125/manuscript

Free tier

NOPLAG2,500 words per check, forever

ITHENTICATENone — no free trial

Crossref Similarity Check

NOPLAGNot a member — independent corpus

ITHENTICATEYes · unlimited use for member journals

Procurement complexity

NOPLAGCredit card · self-serve · monthly

ITHENTICATEPO, multi-month sales cycle for orgs

DETECTION & ACCURACY

Auditable algorithm

NOPLAGApache 2.0 source on GitHub

ITHENTICATEClosed source

Open-web check

NOPLAGGoogle + Brave · 150M+ pages

ITHENTICATE60B+ pages (their crawl)

Scholarly database

NOPLAGOpenAlex + CORE + arXiv + PMC · 700M+ open-access works

ITHENTICATE1,500 publishers + 894M articles (Crossref subscription)

Dissertation database

NOPLAGOpenAlex + CORE coverage

ITHENTICATEProQuest theses + dissertations (proprietary)

False-positive rate published

NOPLAGMeasured against PAN-PC-11 in CI

ITHENTICATENot publicly disclosed

AI-CONTENT DETECTION

AI detection available

NOPLAGComing soon · open methodology

ITHENTICATELimited · not the product focus

Detection method

NOPLAGBinoculars ensemble (open paper, Hans et al. 2024)

ITHENTICATEProprietary · methodology not disclosed

ESL-bias safeguard documented

NOPLAGYes · per-language eval + disclaimer

ITHENTICATENot publicly addressed

Hidden-text / white-on-white

NOPLAGDetected (preprocessing strips invisible glyphs)

ITHENTICATEv2 “red flag” feature — flagship strength

PRIVACY & DATA

Documents used to train models

NOPLAGNever · explicit policy

ITHENTICATENot used for training (per policy)

Right-to-erasure (GDPR)

NOPLAGOne-click in Settings

ITHENTICATEVia institution administrator

EU data residency

NOPLAGAvailable · Pro+

ITHENTICATEAvailable · institutional

Self-host / on-premise

NOPLAGYes · Apache 2.0 engine + Docker

ITHENTICATENo · SaaS only

DEVELOPERS & INTEGRATIONS

Public REST API

NOPLAGYes · OpenAPI 3.0 · $23/mo+

ITHENTICATEYes · publisher API (Editorial Manager + ScholarOne)

Webhooks

NOPLAGYes · Pro+

ITHENTICATEEditorial-system callbacks only

Publisher workflow integration

NOPLAGREST API · custom integration

ITHENTICATEScholarOne + Editorial Manager native

Multilingual coverage

NOPLAGEnglish, Spanish, Portuguese, Polish, and Ukrainian at launch, with more rolling out

ITHENTICATE30+ languages

Feature	NOPLAG	ITHENTICATE
ACCESS & CONTRACTS
Individual access	Yes — sign up in 30 seconds	Yes — direct or via Crossref member journal
Pricing model	Flat-rate · $0 / $23 / $79 / Custom	Per-document credits · $100–$125/manuscript
Free tier	2,500 words per check, forever	None — no free trial
Crossref Similarity Check	Not a member — independent corpus	Yes · unlimited use for member journals
Procurement complexity	Credit card · self-serve · monthly	PO, multi-month sales cycle for orgs
DETECTION & ACCURACY
Auditable algorithm	Apache 2.0 source on GitHub	Closed source
Open-web check	Google + Brave · 150M+ pages	60B+ pages (their crawl)
Scholarly database	OpenAlex + CORE + arXiv + PMC · 700M+ open-access works	1,500 publishers + 894M articles (Crossref subscription)
Dissertation database	OpenAlex + CORE coverage	ProQuest theses + dissertations (proprietary)
False-positive rate published	Measured against PAN-PC-11 in CI	Not publicly disclosed
AI-CONTENT DETECTION
AI detection available	Coming soon · open methodology	Limited · not the product focus
Detection method	Binoculars ensemble (open paper, Hans et al. 2024)	Proprietary · methodology not disclosed
ESL-bias safeguard documented	Yes · per-language eval + disclaimer	Not publicly addressed
Hidden-text / white-on-white	Detected (preprocessing strips invisible glyphs)	v2 “red flag” feature — flagship strength
PRIVACY & DATA
Documents used to train models	Never · explicit policy	Not used for training (per policy)
Right-to-erasure (GDPR)	One-click in Settings	Via institution administrator
EU data residency	Available · Pro+	Available · institutional
Self-host / on-premise	Yes · Apache 2.0 engine + Docker	No · SaaS only
DEVELOPERS & INTEGRATIONS
Public REST API	Yes · OpenAPI 3.0 · $23/mo+	Yes · publisher API (Editorial Manager + ScholarOne)
Webhooks	Yes · Pro+	Editorial-system callbacks only
Publisher workflow integration	REST API · custom integration	ScholarOne + Editorial Manager native
Multilingual coverage	English, Spanish, Portuguese, Polish, and Ukrainian at launch, with more rolling out	30+ languages

PRICING REALITY

What you'll actually pay.

iThenticate's per-document credit pricing isn't a secret — it's published. The figures below are direct from the iThenticate site and from Crossref Similarity Check member docs. Your mileage varies if your publisher already covers it.

noplagMOST FLEXIBLE

Free / self-host$0Apache 2.0 forever
Pro$23/moyearly · 500 pages/mo
Premium$79/moyearly · 5,000 pages/mo
EnterpriseCustomannual · unlimited pages

iThenticatePER-MANUSCRIPT CREDITS

Single manuscript$125one document · ≤25k words
5-revisions pack$125/yr5 revisions of one paper
Crossref member journaldiscountedunlimited · negotiated
Publisher / institutionCustomnegotiated · annual

Turnitin pricing estimates from publicly-disclosed contracts (EdSurge, university procurement records, 2023–2025).

AFTER YOU PUBLISH

iThenticate covers pre-submission. We cover the rest of the research cycle.

If your target journal mandates iThenticate, run that. Noplag is for the other 95% of the research cycle: grant-proposal drafts, dissertation chapters, internal pre-prints, advisor reviews, lab handbooks, conference papers, theses on the way to the journal version. Free up to 2,500 words; Premium $79/mo unlimited. Same engine you'll find at github.com/NoplagLabs/noplag-engine — Apache 2.0, defensible at IRB.

Read the research-cycle guide

FREQUENTLY ASKED

Questions from authors comparing iThenticate.

If my journal requires iThenticate, do I still need Noplag?: Different parts of the pipeline. iThenticate is what your journal will run on the manuscript at submission — that's their decision, not yours, and you can't substitute. Noplag is what you run before that submission — on early drafts, on dissertation chapters, on grant proposals, on the version your co-author sent back. Flat-rate makes the iterative self-check affordable in a way per-credit doesn't.
What's the difference vs Crossref Similarity Check?: Crossref Similarity Check is iThenticate access bundled into Crossref membership — same product, member-discounted access. If your journal is a Crossref member, your editor likely uses CSC. Noplag isn't part of Crossref; we run an independent corpus (OpenAlex + CORE + arXiv + PMC + web). Different content base, different pricing model, different audience.
What about ProQuest dissertations? You don't have those?: Correct — iThenticate's edge here is real. ProQuest's dissertation + thesis database is proprietary, paid, and not in OpenAlex/CORE. For PhD students whose dissertation needs cross-checking against prior US dissertations specifically, iThenticate has the dataset we don't. We cover ~700M open-access scholarly works; ProQuest's ~5M dissertations isn't in that set.
Does Noplag integrate with ScholarOne or Editorial Manager?: Not natively. iThenticate's deep integration with the manuscript-tracking systems (ScholarOne, Editorial Manager) is the result of 15+ years of publisher partnerships under Turnitin's umbrella. We have a REST API + webhooks for custom integration, which is the right shape for self-hosted publisher platforms (OJS / PKP) but won't slot in seamlessly to closed editorial systems.
How is the AI-content detection different?: iThenticate's AI detection is a recent add-on and the methodology isn't published; Noplag's AI detection is coming soon, built on Binoculars (Hans et al. 2024, open paper, reproducible) with per-language calibration and a documented ESL-bias adjustment. It will report AI-likelihood as a signal with per-sentence transparency, not a verdict. Neither tool is perfect — but ours is auditable.
Can I self-host Noplag for sensitive primary-source research?: Yes — the detection engine is Apache 2.0, runs in Docker, no phone-home. Enterprise customers get the cloud corpus as an indexable bundle. iThenticate is SaaS-only with no self-host option, which is a blocker for some IRB-restricted research.
Will iThenticate's 894M article database catch things Noplag misses?: On paywalled subscription content from their 1,500 publisher partners — yes, sometimes. iThenticate has subscription-content licenses we don't. On the open-access universe (the vast majority of recent research, especially post-Plan S), the OpenAlex + CORE + arXiv coverage runs ahead or even. The gap matters most for older journal content behind paywalls; less for the past decade.

Run a draft through Noplag. Send the version your journal wants to iThenticate.

Drop in a chapter, a grant draft, a conference paper. See the report shape against OpenAlex + CORE + web in 60 seconds. Free up to 2,500 words, no signup. You'll know whether the iterative-checking workflow is worth the subscription before you decide anything.

Run a free check Read the research-cycle guide