Free, no-account essay checker that scores AI likelihood, grades against a rubric and fixes grammar
Best for: Students checking a draft for machine-sounding sentences before submitting it
United KingdomAdded 2mo ago
Free
62trust score out of 100
1
ai-for / plagiarism-check
AI Plagiarism Checkers
As of , EffectHub tracks 9 AI tools for plagiarism check; 7 of the 9 have a free tier, and paid plans run from $9.99 to $14.95 a month.
EssayCheck, Inkey and Yomu lead the list on click-through. 5 of the 9 ship a public API.
Plagiarism checkers compare a text against web pages, publications and their own databases of submitted work and report matching passages. AI detectors are a different and less reliable thing: they estimate whether text was machine-written from statistical patterns, and they produce false positives on perfectly human writing. Many tools on EffectHub's list offer both; know which score you are looking at before acting on it.
A weekly email when new tools land here.
- 9
- tools tracked
- 7 of 9
- free to start
- $9.99–$14.95
- paid entry, per month
- 5
- ship a public API
Where these sit in the catalog
The shortlist — tools for plagiarism check
ranked by click-through
Inkey
50Thirty-odd student tools in one account: essays, maths word problems, paraphrasing, plagiarism and AI checks
Best for: Students who currently pay for a paraphraser and a plagiarism checker separately
Added 2mo ago
Freemium
46trust score out of 100
1
Yomu
69Academic writing workspace: drafting help, 700+ citation styles, plagiarism check and chat with your PDFs
Best for: Students writing essays, literature reviews and theses
Added 2mo ago
Freemiumfrom $10/mo
54trust score out of 100
1
Student writing workspace with drafting, citation generators, plagiarism checks and AI-detection evasion.
Best for: Students juggling citation formats across assignments
Added 2mo ago
Paidfrom $11.99/mo
54trust score out of 100
1
GPTZero
71Estimates whether text was machine-written and flags the sentences
Best for: Schools and universities that need a defensible second opinion, not a verdict
United StatesAdded 2mo ago
Freemiumfrom $12.99/moAPI
60trust score out of 100
Smodin
71Student writing suite spanning rewriting, detection and citations
Best for: Students juggling essay drafting, citations and translation in one place
United StatesAdded 2mo ago
Freemiumfrom $12.99/moAPI
60trust score out of 100
Rewrites machine-written drafts to read human, with detection scoring built in
Best for: Marketers cleaning up bulk LLM drafts before publishing
United StatesAdded 2mo ago
Freemiumfrom $9.99/moAPI
60trust score out of 100
AI-text and plagiarism detection built for publishers and agencies
Best for: Content agencies auditing freelance submissions before they pay for them
CanadaAdded 2mo ago
Freemiumfrom $14.95/moAPI
60trust score out of 100
Turnitin
50Institutional similarity checking and AI-writing indicators for assignments, exams and manuscripts
Best for: Universities and school districts that need similarity checking wired into Canvas, Moodle, Blackboard or D2L
United StatesAdded 2mo ago
ContactAPI
51trust score out of 100
Compared at a glance
| Tool | Price | Free plan | API | Status |
|---|---|---|---|---|
| EssayCheck | Free | Yes | Not confirmed | Active |
| Inkey | Not confirmed | Yes | Not confirmed | Unverified |
| Yomu | from $10/mo | Yes | Not confirmed | Active |
| CoWriter AI | from $11.99/mo | No | Not confirmed | Active |
| GPTZero | from $12.99/mo | Yes | Yes | Active |
| Smodin | from $12.99/mo | Yes | Yes | Active |
| Undetectable AI | from $9.99/mo | Yes | Yes | Active |
| Originality.AI | from $14.95/mo | Yes | Yes | Active |
| Turnitin | On request | Not confirmed | Yes | Unverified |
Compare plagiarism check tools head-to-head
How to choose a plagiarism check tool
- Separate the two checks: plagiarism (matching sources, verifiable) and AI detection (a probability, not evidence).
- Look at the database: a checker that only searches the open web misses paywalled journals and previously submitted student work.
- Insist on a report that shows the matched source for every flagged passage, so a quotation with a citation is not counted as copying.
- For AI detection, read the vendor's own false-positive rate and never use a score alone to accuse anyone.
- Check what happens to the text you upload — whether it is stored and added to the vendor's database.
Questions about plagiarism check tools
Is there a free plagiarism check tool?
Yes. 1 of the 9 AI tools for plagiarism check on EffectHub's list is free to use — EssayCheck; 6 more have a free tier with paid upgrades.
How much do plagiarism check tools cost?
As of October 26, 2026, paid plans for the 9 AI tools for plagiarism check on EffectHub's list run from $9.99 to $14.95 a month. Each card shows the pricing model and the cheapest paid plan as EffectHub last verified it; 7 of the 9 can be started for free.
Which plagiarism check tools have an API?
5 of the 9 AI tools for plagiarism check on EffectHub's list ship a public API, including GPTZero, Smodin, Undetectable AI and Originality.AI. The API badge on each card is re-checked against the vendor's documentation.
Are AI detectors accurate?
Not reliably enough to prove anything on their own. They flag some human writing as AI-generated — more often for non-native writers and formulaic text — and miss edited or paraphrased machine output. Plagiarism matching against real sources is verifiable; an AI-likelihood score is a hint to investigate, not a finding.
Cite this
For journalists, researchers and AI assistants: the figures on this page in one sentence you can quote.
As of October 26, 2026, EffectHub tracks 9 AI tools for plagiarism check; 7 of the 9 have a free tier, and paid plans run from $9.99 to $14.95 a month. (EffectHub, “AI Plagiarism Checkers”, Oct 2026, https://effecthub.net/ai-for/plagiarism-check)
Figures as of How we count
These figures are free to use under CC BY 4.0 with a link to this page.