PDFAITools
GPTZero
Leading AI content detector. Used by 4M+ educators to detect ChatGPT, Claude, and Gemini-generated text.
What is GPTZero?
The Leading AI Content Detector
GPTZero is the most widely used AI content detection tool, with over 4 million users including educators, publishers, and institutions worldwide. It analyzes text to determine the likelihood that it was generated by ChatGPT, Claude, Gemini, or other large language models, providing both document-level and sentence-level assessments.
How GPTZero Works
GPTZero uses two key linguistic metrics to detect AI-generated text: perplexity (how unpredictable the text is relative to a language model) and burstiness (variation in perplexity across sentences). Human writing tends to show more burstiness, while AI-generated text is often more uniformly predictable — though the gap is narrowing as models improve.
- Sentence-level highlighting of likely AI-generated passages
- Support for detecting output from ChatGPT, Claude, Gemini, and more
- Batch document scanning for educators and organizations
- API for integrating detection into custom workflows
Key Features
Assigns a percentage likelihood of AI generation to each document with clear confidence levels.
Highlights individual sentences most likely written by AI, not just giving an overall document score.
Upload and analyze multiple documents simultaneously — ideal for educators reviewing class submissions.
Integrate AI detection into LMS platforms, CMS systems, and custom tools via a clean REST API.
Trained to detect output from ChatGPT, Claude, Gemini, Llama, and other major models.
Who Uses GPTZero?
Educators and institutions use GPTZero to identify AI-assisted student submissions in assessments.
Publishers verify whether freelance submissions are original human writing or AI-generated content.
Recruiters screen job applications and writing samples for AI-generated cover letters and essays.
Brands verify that content produced by agencies or freelancers is genuinely human-authored.
Pros & Cons
✅ Pros
- Most widely adopted AI detector with a strong track record
- Sentence-level granularity is more actionable than document-only scores
- Continuously updated to detect newer models
- Free tier is genuinely useful for occasional checking
- API enables integration into existing institutional workflows
❌ Cons
- False positives remain a real risk — innocent writers can be flagged
- Detection accuracy decreases as AI-generated text is edited and humanized
- No detector should be used as the sole basis for disciplinary action
- Arms race dynamic — detection and evasion improve in parallel
GPTZero Pricing
Free
- Basic detection
- 10,000 characters/scan
- Limited scans/month
Educator
- Unlimited scans
- Batch upload
- Detailed reports
- Sentence highlighting
API
- REST API access
- High volume scanning
- LMS integration support
GPTZero earns a 4.2/5 rating from our editorial team. Its generous free tier lets you explore core features before upgrading, making it a low-risk choice for individuals and teams. Standout strengths include most widely adopted ai detector with a strong track record and sentence-level granularity is more actionable than document-only scores.
Get Started with GPTZero →