llms.txt: the complete 2026 guide
The llms.txt file is the entry point LLMs (ChatGPT, Perplexity, Claude, Gemini) use to quickly understand your website. Done right, based on our internal observations (OMNIRK, 80+ sites sample 2025-2026), it can 2-3x AI citations within 6 to 8 weeks.
What is llms.txt?
A Markdown file at /llms.txt that summarizes your site: entity, services, key pages, citable facts. The robots.txt of generative AI.
Official 2026 spec
Defined by llmstxt.org: H1 title (entity name), blockquote description, then H2 sections for pages/services/facts. Recommended limit: 8,000 characters.
5 mistakes to avoid
1) Empty lists, 2) hollow marketing copy, 3) broken URLs, 4) missing dates, 5) no /llms-full.txt with the full corpus.
Our OMNIRK template
We publish an open-source template used by 120+ sites: entity + services + 10 numeric facts + FAQ. Downloadable at omnirk.com/llms.txt.
FAQ
- Is llms.txt an official standard?
- A de facto standard adopted by Perplexity, Anthropic and OpenAI in 2025. Not yet W3C but recognized by every major AI crawler.
- Maximum size?
- 8,000 characters for llms.txt (summary), unlimited for llms-full.txt (full corpus).
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