QuillBot is independently evaluated on RAID, a third-party benchmark covering ChatGPT, GPT-4, GPT-5, Claude, Gemini, Mistral, Llama, and more.

QuillBot's free AI writing detector is built on advanced LLM-based linguistic pattern analysis, continuously trained on large datasets to stay current with the latest AI writing systems.

Our models are designed to deliver high accuracy across all content types, lengths, and writing styles, while minimizing false positives to ensure human-written content is not wrongly flagged.

Key things that make our detection reliable:

Up-to-date models: Keeps pace with the latest AI writing tools like ChatGPT as they evolve
Broad model coverage: Detects content from all major AI systems including ChatGPT, Gemini, Claude, and Copilot
Low false positive commitment: Built to avoid flagging human writing
Multilingual support: Detects AI text across multiple languages

What affects accuracy:

Longer texts (300+ words) produce more reliable scores than short inputs
Heavily paraphrased or lightly AI-edited content is harder to detect for any AI checker
Formulaic human writing (academic definitions, legal copy, structured templates) can score higher than expected for any AI writing detector

Note that no AI Detector can provide 100% accuracy. As language models like ChatGPT continue to evolve, detection tools must continuously adapt to keep up, which is why our models are regularly retrained and refined. Results are probability estimates, not verdicts. Use them as one input in a wider review.