How I Built an AI Content Detector Without Using Any AI

Everyone's paying $29/month for GPTZero. I built my own for free using nothing but math and pattern recognition. Here's exactly how. The Problem I was reviewing freelance writing submissions and couldn't tell which ones were AI-generated. The commercial detectors exist (GPTZero, Originality.ai, Copyleaks) but they all share the same problem: they're expensive, they require API keys, and they're black boxes. I wanted something I could understand, modify, and run for pennies. So I built it myself. The Insight: AI Writes Like a Robot Pretending to Be Human After reading hundreds of ChatGPT outputs side-by-side with human writing, I noticed patterns. Not subtle ones. Obvious, measurable ones: 1. AI sentences are weirdly uniform in length. Humans write a 5-word sentence, then a 40-word sentence. AI averages around 15-20 words, consistently. 2. AI doesn't "burst." In linguistics, burstiness means having clusters of short sentences followed by longer ones. Humans do this naturally. AI smooths