The Slop Index: Which AI Model Writes the Least Like AI?

A new benchmark called the Slop Index scores 39 frontier AI models on how much their writing resembles AI-generated text, ranking #1 as the sloppiest model on the board. The index measures each model's distance from genuine human writing collected before ChatGPT existed — workplace email from 2000–2002, pre-2022 tweets, essays and chat logs — and counts specific phrases against how often real people used them before 2022. No LLM judges the outputs; scores are mechanical, supplemented by a blind human vote arena in which anyone can compare two samples from the same task.

The Slop Index A reference benchmark of how much each AI writes like AI slop. Measured by machine and by blind human vote. Have you ever gotten an email that opened with “I hope this finds you well,” offered exactly three tidy bullet points, and closed by inviting you to not hesitate? You knew. Everyone knows. Every frontier model can write; the question is whether it writes like a person or like AI slop . The index at right is the live answer. Thirty-nine frontier models, scored against genuine human writing collected before ChatGPT existed , and by a blind human vote that anyone can join. Higher means the writing reads more like a chatbot, so 1 is the sloppiest model on the board . No LLM judges anything. a live benchmark You already know it when you read it The underlined phrases are among the tells the index counts, each measured against how often real people actually used it before 2022, not against a model’s guess. No LLM judges. No vibes. Just measurement. Slop is distance from genuine human writing collected before ChatGPT existed , so no model could have shaped the yardstick. The corpus: real workplace email from 2000–2002, tweets from before 2022, essays and chat logs that predate generative AI entirely. Every number is mechanical, plus one big input: people . Think you can spot the slop? The board is the machine’s verdict. The arena collects yours: two blind samples from the same task, one sloppier than the other. Every vote moves the live human axis of the score.