Side by side
| Feature | GPTZero | Undetectable AI |
|---|---|---|
| What it does | Free AI detector that scores text for AI-generated content, sentence by sentence, for educators, students and writers. | Detects AI-generated text and images and rewrites AI writing so it reads as human, for students, writers and professionals. |
| Price from | not listed | 5.00 USD/mo |
| Free plan | yes | trial |
| Platforms | web, chrome, api | web, chrome, api |
| API | yes | yes |
GPTZero: key features
- Overall AI score with sentence-by-sentence detection
- Detection of text from ChatGPT, GPT-5, Gemini, Claude and Llama
- Writing replay showing the typing process and copy-paste activity
- Plagiarism checker
- Grammar check and writing feedback
- Chrome extension and Google Docs integration with Canvas and Google Classroom
Undetectable AI: key features
- Detects AI-generated text and highlights suspicious sentences
- Humanizer rewrites AI text to read more naturally
- AI image detection for checking whether a picture is AI-made
- AI audio/voice detection
- Fake PDF detection
- Chrome extension that works inside Google Docs, Gmail and web pages
FAQ
Is GPTZero or Undetectable AI better?
It depends on the job - compare prices, free plans and features in the table above.
Are GPTZero and Undetectable AI free?
GPTZero: Yes, there is a free plan. Free basic AI detection by pasting text into the scanner; the homepage advertises it as free. Paid features are not detailed in the provided text. Undetectable AI: There is a free trial. Free trial limited to 250 words; additional usage requires a paid plan.