SlopShape spots AI-written commercial pages by structure, not word choice

Training a model to identify AI-generated web content from structure alone

SlopShape uses 187 structural features—how info is ordered, what evidence appears, what voice is used—to detect AI-generated commercial blog posts without looking at word-level signals. Trained on 2,250 pre-ChatGPT human posts and 11,250 AI mirrors from five frontier models, it hits 98.0 macro-F1 on held-out companies. When every AI post is reworded by its own model, F1 stays at 98.1. It also attributes 79.3% of AI posts to the correct source model. Human posts occupy rare structural patterns. Code and artifacts are public.