Pulse.
Human writing has a pulse. Machine writing flatlines. Paste your text and Pulse charts every sentence as a bar, so you can see the rhythm: the spikes and dips of a real writer, or the flat, even wall of a machine.
Why rhythm gives the machine away
Models write to the middle. Left alone, they produce sentence after sentence of roughly the same length, and that even cadence is one of the most reliable tells of machine text. A person writes differently. They follow a long, winding thought with a short, blunt line. They ask a question. They land a three-word sentence for effect.
Pulse measures the variance in your sentence lengths and draws it. A lively, spiky chart is the sound of a human thinking on the page. A flat one is the first thing to fix, and Typographer grades it live while you write.