Documentation

Cat Documentation

This is your complete guide to understanding and caring for cats. Browse through the sections below to learn everything you need to know about these wonderful creatures.

Available Sections

Cat Basics: Essential information for new cat owners
Cat Behavior: Understanding feline psychology and communication

News coverage

cats.txt was published in September 2025. It has since been specified twice, adopted by real websites, written up by the trade press, argued about at conferences and cited — sincerely — as an AI optimisation tactic. This page records that.

Entries are ordered by date. Where a publication date could not be confirmed from the source itself, the month is given rather than a specific day.

September – October 2025

cats.txt Specification (Draft v1.0)

markwilliamscook.com · Mark Williams-Cook · 18 September 2025 · Specification

Test 2026-08

Search is how you get into AI answers or Testing LLMS for cats.txt

TL;DR — I probed fifteen LLMs for the contents of the novel cats.txt file, with and without web search, on a single date. With search: 59–60 of 60 correct. Without search: zero, including from the four to five models that demonstrably hold other facts from the same domain in memory. A minority of models knew the file existed without searching — apparently from third-party commentary rather than the file itself — but not one could state anything it contained. Retrieval is the layer that responded. Training was not measurably touched. GEO, at least in this case, is search.

RFC draft

cats.txt: A Standard for Providing Website Information to Chatbots

Abstract

This document defines cats.txt, a machine-parsable file format for web servers to provide essential metadata about their site to automated agents, particularly chatbots and Large Language Models (LLMs). The file, located at a well-known URI, uses a structured subset of Markdown to convey information such as the site’s purpose, key links, and an optional semantic embedding vector. The name is derived from the French “chat” (cat), which is also the root of “chatbot”. The specification includes a mandatory cat image for parser validation, acknowledging the internet’s deep-rooted cultural affinity for felines.

Participating sites

This Internet standard is already widely adopted.

Many of the top 48'113 websites are using this standard to improve their visibility in Chatbot responses. Some are choosing to use cloaking to only make this file available to participating crawlers, so you will probably not be able to find them yourself.

If you’d like to have your site mentioned here, together with a prominent link to your cats.txt file, please use this form to let us know.