GPTZero
AI DetectionAI detection tool for spotting ChatGPT and LLM-generated content
Overview
GPTZero emerged from Princeton University as one of the first dedicated AI detection tools, gaining rapid adoption when ChatGPT usage exploded in early 2023. Built by Edward Tian and Alex Cui, the tool focuses specifically on identifying text generated by large language models rather than traditional plagiarism detection. Unlike tools that evolved from existing plagiarism checkers, GPTZero was purpose-built for the AI detection challenge.
The platform uses perplexity and burstiness analysis to identify AI-generated content. Perplexity measures how predictable text is to a language model, while burstiness examines variation in sentence complexity and length. Human writing typically shows more variation and unpredictability than AI-generated content, though this gap narrows as AI models improve.
GPTZero competes directly with Originality.ai and Copyleaks in the AI detection space, but positions itself as more accessible with a generous free tier and educational focus. The tool has processed millions of documents since launch and claims detection capabilities across ChatGPT, Claude, Gemini, and other major language models.
Key features
Per-Sentence Analysis
Breaks down text at sentence level to identify specific portions that may be AI-generated, providing granular detection insights.
Multi-Model Detection
Identifies content from ChatGPT, Claude, Gemini, and other major language models with model-specific accuracy ratings.
Perplexity and Burstiness Metrics
Uses linguistic analysis to measure text predictability and sentence variation patterns that indicate AI generation.
Chrome Extension
Browser plugin enables real-time detection across web pages, emails, and documents without leaving your workflow.
Batch Processing
Upload multiple documents simultaneously for bulk AI detection analysis, useful for content audits and quality checks.
API Integration
RESTful API allows integration into content management systems, editorial workflows, and automated quality pipelines.
Pricing
| Plan | Price | Includes |
|---|---|---|
| Free | $0 | 3 scans/month, basic detection, Chrome extension |
| Essential | $10/month | 150 scans/month, API access, batch processing, detailed reports |
| Premium | $16/month | 300 scans/month, priority support, advanced analytics, team features |
| Professional | $23/month | 500 scans/month, white-label options, custom integrations, dedicated support |
FAQ
How accurate is GPTZero at detecting AI-generated content?
GPTZero claims 99%+ accuracy on purely AI-generated text, but accuracy drops significantly with human-edited AI content or mixed human-AI writing. Real-world accuracy varies based on content type and AI model used.
Can GPTZero detect content from all AI writing tools?
GPTZero detects most major language models including ChatGPT, Claude, and Gemini, but struggles with newer models and heavily edited AI content. It's less effective against paraphrasing tools and AI humanizers.
Does GPTZero work for non-English content?
GPTZero primarily focuses on English text detection with limited support for other languages. Detection accuracy is significantly lower for non-English content.
Can GPTZero identify mixed human-AI content?
GPTZero provides sentence-level analysis to identify AI-generated portions within human-written text, but accuracy decreases when AI content is heavily edited or integrated with human writing.
Is GPTZero suitable for academic plagiarism detection?
GPTZero was designed for educational use but should supplement, not replace, traditional plagiarism detection. False positives can occur with certain writing styles or technical content.
Review Sentiment
24 reviews across 1 source
Bottom line
One of the better values in ai detection. GPTZero delivers per-sentence AI detection highlighting shows for just $10/mo, earning a 4.3/5 rating. The downside: false positive rate can be high.
People love
- +Per-sentence AI detection highlighting shows exactly which parts are flagged as AI-generated
- +Supports detection across multiple LLMs including GPT-4, Claude, and Gemini
- +Batch file scanning enables checking multiple articles at once
Common complaints
- –False positive rate can be high — especially for non-native English writers with structured prose
- –Free tier limited to 5000 characters per scan — Pro starts at $10/mo
- –Detection accuracy decreases significantly for edited or paraphrased AI content
Last updated Feb 2026