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GPTZero vs Copyleaks: catalog facts
GPTZero	Copyleaks
Freemium Free scans up to 10,000 characters, with paid upgrades for advanced features.	Paid A commercial service; the homepage directs organisations to request a demo.
Web, Browser extension	Web
Sentence-level highlighting rather than a single score Writing replay in Google Docs shows how a document was produced	Detects both plagiarism and AI-generated text Checks source code for plagiarism
AI detection is probabilistic and can misclassify human writing Free scans are limited in length	Aimed mainly at institutions and businesses AI detection results are probabilistic and can be wrong
Web application, Browser extension	Hosted service
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked September 26, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.