Hemmingway-1.5: 27B Open-Weight Model Claims 90% Success Rate Against AI Detectors

·2026.10.29 18:27

Key point

The 27B parameter open-weights model is free for non-commercial use and outperforms real human writing in detector evasion tests.

Hemmingway-1.5 is a 27B parameter open-weights model released by HemmingwayAI, available for free for non-commercial use.
The model passes the world's best AI detectors 90% of the time, specifically achieving a 90% pass rate on GPTZero at every thinking level.
For comparison, real human writing passes the same detectors 86% of the time, while Fable, GPT-6, and Gemini are detected most of the time.
The release includes Mac, Windows, and Android apps, an API, and code, alongside previous models Hemmingway-1 and Hemmingway-1-Unlocked.

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