Topic · GEO and AI visibility

llms.txt specification

The robots.txt of the AI era. Adoption is still under 5%.

Definition

What is llms.txt specification?

llms.txt is a proposed plain-text manifest at /llms.txt that summarizes a website's content for large language model crawlers. The spec, hosted at llmstxt.org, defines a Markdown structure with sections of named links so models can ingest a curated map of the site. In the Q1 2026 tracked corpus, adoption was approximately 4% across the analyzed cohort.

Services that operate this topic

How Xpand Media runs it

Service

Get Your Brand Recommended by AI

Optimize your brand to appear in AI-generated recommendations across ChatGPT, Gemini, Perplexity, and Google AI Overviews.

Industries that care about this

Sector relevance

Vertical

B2B SaaS

B2B SaaS in 2026 buys through ChatGPT and Perplexity before it ever sees Google. If your brand isn't cited in AI answers, demos don't book.

Vertical

AI-native companies

AI-native companies need GEO that names the model, the use case, and the developer adoption signal. Generic positioning loses to specific technical-buyer hooks.

FAQ

Common questions about llms.txt specification

Where does llms.txt live?
At the site root, at the path /llms.txt, served as text/plain. Following the spec, it uses Markdown structure with H1 (site name), blockquote summary, and named sections with link lists.
How is it different from robots.txt?
robots.txt controls crawler access. llms.txt curates content discovery — it tells the model what's worth reading, not whether it can read.
Do AI engines actually use llms.txt?
Adoption is partial. Anthropic publicly references it. OpenAI and Google have not confirmed dedicated parsers but treat it as crawlable plain text. Adding it is low cost and forward-compatible.
Should we also publish llms-full.txt?
Yes if the site has high-volume content. llms-full.txt is the long-form variant that concatenates page content, intended for offline LLM ingestion.
What format do links need to be in?
Standard Markdown: hyphen, space, bracketed link text, parenthesized URL, optional colon-prefixed description. Other formats (em-dash separated, plain URL lists) may fail spec parsers.

Talk to the team

Run llms.txt specification inside a live engagement.

Book a strategy call →Read the State of GEO 2026 →

Spinning up

What is llms.txt specification?

Common questions about llms.txt specification

Where does llms.txt live?

At the site root, at the path /llms.txt, served as text/plain. Following the spec, it uses Markdown structure with H1 (site name), blockquote summary, and named sections with link lists.

How is it different from robots.txt?

robots.txt controls crawler access. llms.txt curates content discovery — it tells the model what's worth reading, not whether it can read.

Do AI engines actually use llms.txt?

Adoption is partial. Anthropic publicly references it. OpenAI and Google have not confirmed dedicated parsers but treat it as crawlable plain text. Adding it is low cost and forward-compatible.

Should we also publish llms-full.txt?

Yes if the site has high-volume content. llms-full.txt is the long-form variant that concatenates page content, intended for offline LLM ingestion.

What format do links need to be in?

Standard Markdown: hyphen, space, bracketed link text, parenthesized URL, optional colon-prefixed description. Other formats (em-dash separated, plain URL lists) may fail spec parsers.