ZeroGPT is a free, ad-supported detector for pasted text with a character limit per check. For a full research paper or thesis, PaperCheck checks the whole Word or PDF file, marks each flagged sentence with the reason and adds a plagiarism check.
Written by Adithyan, a student who builds PaperCheck. Last updated 31 October 2026.
Pasting a thesis in pieces loses the context between sections, and a single overall percentage does not tell you which sentences to fix. Independent reviewers have also reported high false-positive rates on human writing.
On 909 AI-written and 469 human-written papers it had never seen, PaperCheck caught 98% of the AI papers and wrongly flagged 0.43% of the human ones. No detector is proof.
Reviewers report it flags a lot of human writing. Use a checker tested on academic text and look at which sentences are flagged.
Yes, 5 checks a month up to 20,000 words each after Google sign-in.
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PaperCheck is not affiliated with Turnitin, GPTZero, papercheck.in or papercheck.ai. Scores from any detector are estimates, not proof.