Comparison
| Tool | Price from | Free plan | Category |
|---|---|---|---|
 Undetectable AI | 5.00 USD/mo | trial | AI detectors |
 GPTZero | not listed | yes | AI detectors |
 Originality.ai | 12.95 USD/mo | yes | AI detectors |
 ZeroGPT | not listed | yes | AI detectors |
 Turnitin | not listed | ? | AI detectors |
 Copyleaks | 13.99 USD/mo | trial | AI detectors |
 QuillBot | not listed | ? | Writing & editing |
 AI or Not | 5 USD/mo | yes | AI detectors |
 Winston AI | 9 USD/mo | trial | AI detectors |
Each alternative in short
1. GPTZero
Free AI detector that scores text for AI-generated content, sentence by sentence, for educators, students and writers.
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.
2. Originality.ai
AI detector and content checker that flags AI-generated text and plagiarism for writers, editors, teachers and publishers.
Yes, there is a free plan. Basic plan with AI detection only: 3 scans per day, limit of 2,000 words per scan, file upload (docx, pdf, doc). No subscription required.
3. ZeroGPT
Online AI content detector that flags AI-written text and images, plus paraphrasing, grammar and plagiarism tools for writers, students and educators.
Yes, there is a free plan. Free plan, no credit card needed, with limited access to the tools (the 15,000-character limit shown on the homepage applies to the detector input).
4. Turnitin
Academic integrity platform that detects plagiarism and AI-generated writing and supports grading and feedback for schools and universities.
The vendor does not state this clearly on the homepage or pricing page.
5. Copyleaks
Detects AI-generated and plagiarized text, images, and video, mainly for schools, publishers, and enterprises protecting content and IP.
There is a free trial. Free start for students (Start for Free / Start now for free); scan credits are limited on the individual plans.
6. QuillBot
AI writing suite for paraphrasing, grammar checking, AI detection, and content creation, aimed at writers, students, and professionals.
The vendor does not state this clearly on the homepage or pricing page.
7. AI or Not
Detects AI-generated text, images, music, video and deepfakes, for individuals and businesses via web or API.
Yes, there is a free plan. 5 USD in free credits, 1M words of AI text detection per month, 20 AI image checks and an API key included.
8. Winston AI
AI content detector and plagiarism checker that flags text and images generated by ChatGPT, Claude, Gemini and other models, for educators, publishers and writers.
There is a free trial. 14-day trial with 2,000 credits, including AI content detection, AI image detection, document scanning and PDF reports.
FAQ
What is the best alternative to Undetectable AI?
The most popular option in the same category is GPTZero. See the comparison table above.