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Head-to-head · AI Plagiarism Checkers

Turnitin Similarity vs Noplag

  • Updated Oct 2026
  • Both researched from official sources
  • 4 checks side by side
Higher score Turnitin Similarity #3 in AI Plagiarism Checkers 9.2/10 Pricing on request ✓ 3 of 3 features Visit Turnitin
Noplag #8 in AI Plagiarism Checkers 8.4/10 Free plan · 14-day trial Free planFree trial✓ 1 of 3 features Visit Noplag

Turnitin Similarity leads on 0 checks, Noplag on 0, and 4 are even. Who comes out ahead on the 4 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreTurnitin Similarity · 9.2/10
  • Free planonly Noplag
  • Free trialonly Noplag
  • Most featuresTurnitin Similarity · 3 of 3

Turnitin Similarity scores higher on our rubric for ai plagiarism checkers: 9.2 against 8.4 out of 10; our editors rank them #3 and #8.

Turnitin Similarity is the better fit for institutions prioritizing established similarity workflows. Noplag is the better fit for technical users wanting open-source self-hosting.

  • Turnitin Similarity fits best

    Institutions prioritizing established similarity workflows

  • Noplag fits best

    Technical users wanting open-source self-hosting

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Side by side

Feature Turnitin Similarity 9.2/10 Visit ↗ Noplag 8.4/10 Visit ↗
At a glance
Editor score 9.2 8.4
Ranking #3 in AI Plagiarism Checkers #8 in AI Plagiarism Checkers
Best for Institutions prioritizing established similarity workflows Technical users wanting open-source self-hosting
Pricing model Paid Free plan + paid
Starting price Pricing on request $9.99/mo
Free plan Not checked yet ✓ (best)
Free trial — 14 days
Deployment Cloud Cloud, Desktop
Platforms Web Web, Windows, macOS, Linux
Integrations 4 integrations 4 integrations
Features Turnitin Similarity 3/3 · Noplag 1/3
LMS integrations ✓ (best) Not checked yet
API access ✓ ✓
AI writing check ✓ (best) Not checked yet
Specs
Source coverage Web_academic_and_publisher Not checked yet
Maximum document words Not checked yet Not checked yet
Supported file formats DOC, DOCX, XLS, XLSX, PPT, PPTX, PostScript, PDF, HTML, HWP, RTF, ODT, WordPerfect, TXT Not checked yet
Report export Pdf Not checked yet
Our review
Pros
  • Compares work against student, web, scholarly, and publisher content
  • Provides match groups, source comparisons, filtering, and integrity flags
  • Supports LMS workflows, PDF reports, and API submission and retrieval
  • Checks live web, academic papers, Common Crawl, Wikipedia, and proprietary databases
  • Open-source Apache 2.0 engine supports self-hosting
  • REST API, webhooks, LTI 1.3, and major LMS integrations
Cons
  • Institutional pricing requires contacting sales
  • AI-writing detection requires the Turnitin Originality add-on
  • Designed for institutional workflows rather than standalone individual use
  • No AI-generated-text detection
  • Free and paid checks cap documents at 2,500 to 50,000 words
  • Advanced features require paid plans or Enterprise deployment
Our verdict

Turnitin Similarity is an institutional originality-checking product for schools, colleges, universities, instructors, administrators, and students. It compares submissions against student papers, current and archived web pages, scholarly…

Read the review →

Noplag is a plagiarism checker for students, educators, researchers, publishers, and businesses. It accepts pasted text, document uploads, and URLs, then compares content with live web pages, academic papers, Common Crawl, Wikipedia, and…

Read the review →
  1. Turnitin SimilarityAI Plagiarism Checkers 9.2Pricing on request
  2. NoplagAI Plagiarism Checkers 8.4Free plan · 14-day trial

Strengths and trade-offs

  • Turnitin Similarity — where it wins

    • Compares work against student, web, scholarly, and publisher content
    • Provides match groups, source comparisons, filtering, and integrity flags
    • Supports LMS workflows, PDF reports, and API submission and retrieval

    Where it doesn't

    • Institutional pricing requires contacting sales
    • AI-writing detection requires the Turnitin Originality add-on
    • Designed for institutional workflows rather than standalone individual use

  • Noplag — where it wins

    • Checks live web, academic papers, Common Crawl, Wikipedia, and proprietary databases
    • Open-source Apache 2.0 engine supports self-hosting
    • REST API, webhooks, LTI 1.3, and major LMS integrations

    Where it doesn't

    • No AI-generated-text detection
    • Free and paid checks cap documents at 2,500 to 50,000 words
    • Advanced features require paid plans or Enterprise deployment
  • Turnitin Similarity9.2/10 · Pricing on request

    A broad academic similarity workflow with LMS, reporting, filtering, and API support.

    Visit TurnitinFull verdict →
  • Noplag8.4/10 · Free plan · 14-day trial

    A self-hostable plagiarism checker with broad source coverage but no AI detection.

    Visit NoplagFull verdict →

More comparisons

All AI plagiarism checkers comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update