llms.txt
llms.txt is a proposed text file, similar in format to robots.txt, that a site can publish to summarize its content for AI models, but as of mid-2026 no major AI system reads or uses it, so it has no effect on AI visibility.
llms.txt is a proposal for a plain-text file, formatted a bit like robots.txt, that a website places at its root to hand AI models a curated summary of its content: what the site is, what pages matter, and what a model should read to understand it. The idea, on paper, is to save a model the work of crawling and parsing a whole site.
Here's the honest state of it as of mid-2026: no AI system currently uses llms.txt. Google's John Mueller said this directly in June 2025, comparing it to the old keywords meta tag, a file webmasters fill in earnestly that nothing on the other end actually reads. Google's Gary Illyes said Google does not support llms.txt and has no plans to. When people noticed some Google-owned sites serving an llms.txt file anyway, Mueller clarified that Google's own Search team neither uses nor endorses it, an internal CMS had simply added it.
So if you're being sold llms.txt optimization as a way to improve AI visibility, you're being sold folklore. There's a proposal, there's a file format, and there's no evidence any major answer engine reads it or changes its behavior because of it. Spending time or money on it doesn't make your business more likely to be cited or recommended.
The things that actually do relate to how a model reads your site, if any: whether your pages are crawlable at all, whether the facts on them are stated plainly, and whether the same information appears consistently across your site and the directories that feed AI answers. None of that requires an llms.txt file.
Keep exploring the glossary
- Generative Engine Optimization (GEO)Generative Engine Optimization (GEO) is the practice of shaping content so AI chatbots like ChatGPT, Gemini, and Perplexity cite or recommend it when they generate an answer, rather than optimizing for a ranked list of links.
- Answer Engine Optimization (AEO)Answer Engine Optimization (AEO) is the practice of structuring content so answer engines such as ChatGPT, Perplexity, and Google's AI Overviews can extract a direct answer from it and attribute that answer to your business.
- Large Language Model Optimization (LLMO)Large Language Model Optimization (LLMO) is the practice of making content easy for a large language model to retrieve, understand, and repeat accurately, so it names your business when answering a customer's question.
Common questions about llms.txt
- Should I add an llms.txt file to my site?
- It won't hurt you, but it won't help either. Google has stated plainly that no AI system uses it as of mid-2026. Spend the time on your actual pages and listings instead.
- Why do some sites have an llms.txt file if it doesn't work?
- Some site owners adopted it hoping it would become a standard, the way robots.txt did. Even Google's own Search team said an internal CMS added one to some Google-owned sites without Search's involvement, and clarified it doesn't use or endorse it.