DetectGPT

DetectGPT is a web and iOS AI content detector (with a companion iOS app) for teachers, students, writers, freelancers, and teams who need to check whether text is human-written or AI-generated.

Key capabilities include:

• AI text detection for content from models such as ChatGPT, GPT-4, and Gemini, and others. It provides probability scores and claims up to 99% accuracy on the website (with earlier references to 95% accuracy based on initial experiments). It supports text input and file uploads, and is available in 50+ languages.
• Plagiarism checking to ensure originality and content integrity.
• Additional tools including readability scoring, fact checking, and the ability to generate "Human-Written" certificates with shareable analysis links.
• AI Detection API for organizations and teams wanting to integrate detection into their own tools and workflows.

Pricing: Freemium. Free trial scans up to 3,000 words. Paid plans start at $15/month (Essential), $29/month (Pro), and $59/month (Team), with a yearly option advertised as 6 months free; iOS in-app purchases are listed from $4.99 to $39.99.

Notable for its detection approach that builds on Stanford’s open-source DetectGPT research, using a zero-shot probability curvature method intended to avoid retraining for new models.