AI Text Detector compared with GPTZero, Turnitin and Originality.ai| AI Text Detector | GPTZero | Turnitin | Originality.ai |
|---|
| Detection basis: A RoBERTa base classifier fine-tuned on outputs of the 1.5B-parameter GPT-2 model. It predicts whether a text came from GPT-2 and returns probabilities for real versus fake text. | Detection basis: Scores pasted or uploaded text and highlights sentences flagged as likely AI-generated. The vendor names ChatGPT, Claude and Gemini among the covered models, and adds a plagiarism checker and an authorship replay feature. | Detection basis: Reports an overall percentage and highlights suspected segments inside the Similarity Report. It also flags text that may have been reworded by paraphrasing tools, a check available in English only. | Detection basis: Offers AI detection on every plan, including the free tier. Paid plans add plagiarism checking, full-site and URL scans and scan history. |
| Limits and validity: The developers report approximately 95% accuracy on text from the 1.5B GPT-2 model and say this is not enough for standalone detection. The model card warns against using it as a ChatGPT detector, and larger generators are harder to detect. | Limits and validity: Accuracy figures are the vendor own claims, and the vendor notes that no AI detector is perfectly accurate. Full language support is stated for English, German, Portuguese, French and Spanish. | Limits and validity: Needs at least 300 words of prose, at most 30,000 words and under 100 MB per file. The vendor aims for a false positive rate under 1% on documents with more than 20% AI writing, and scores below 20% appear only as an asterisk. | Limits and validity: The free tier allows 3 scans per day and 2,000 words per scan, with file upload of docx, pdf and doc. |
| Licence and cost: The model is published on Hugging Face under the MIT licence, so the weights can be downloaded and inspected. | Licence and cost: A free scan works without an account, and scans above 10,000 characters need a free account. The team plan lists an allowance of 500,000 words each month per member with a minimum of 2 seats. | Licence and cost: Licensed to institutions, as part of Turnitin Originality or as an add-on for iThenticate 2.0. Only instructors and administrators see the indicator. | Licence and cost: Pro and Enterprise are paid subscriptions, billed monthly. One credit equals 100 words, and the vendor page shows some inconsistent figures, so check current prices. |
| Integration and API: No API is documented on the model card. The model is intended for research on synthetic text generation and detection. | Integration and API: An API with ready-to-use code in 17 programming languages is offered, with a Chrome extension and integrations such as Google Classroom, Canvas and Zapier. | Integration and API: LTI integrations and a RESTful API are listed for Turnitin Originality. | Integration and API: API access is listed under the Enterprise plan, and a Chrome extension is included on paid plans. |
| Intended use: The model card excludes serious academic misconduct allegations from the intended use. It suits studies of how GPT-2 era detectors behave. | Intended use: Stated users include educators, students, publishers, recruiters and marketers. | Intended use: Built for educational institutions. The vendor states the score should not be the sole basis for action and does not determine misconduct. | |
