What llms.txt is
llms.txt is a proposed standard that lives at the root of your domain, like robots.txt or sitemap.xml. It is a markdown file that tells language models what your site is, who runs it, and which URLs are the most important sources of truth.
Unlike a sitemap, which is an exhaustive list optimized for machines, llms.txt is a curated brief optimized for reasoning systems. Think of it as the executive summary you would hand to an analyst before they wrote a report on your company.
Why it matters now
- Context windows are finite. Even the largest LLMs cannot read your whole site.
- Retrieval is biased toward whatever is easy to parse. llms.txt is the easiest possible parse.
- Agent frameworks (LangChain, LlamaIndex, custom assistants) increasingly check for it first.
- Shipping it costs nothing and signals technical competence to every crawler that sees it.
Anatomy of a good llms.txt
A useful llms.txt starts with a one-paragraph description of the site, lists the key sections with one-line summaries, and links to the canonical URLs for each. Avoid marketing fluff. Write the way you would brief a new analyst on day one.
Common mistakes
- Dumping the entire sitemap into llms.txt. It defeats the purpose.
- Writing marketing copy instead of factual summaries.
- Forgetting to update it when the site structure changes.
- Hosting it anywhere other than the root of the domain.
Generate one in 60 seconds
OptimAIze crawls your site, infers the structure, and outputs a deploy-ready llms.txt along with robots.txt entries for every major AI crawler. Drop both files at your domain root and you are ahead of 95 percent of the web.