llms.txt is a proposed convention for placing a plain text file at your website's root (yoursite.com/llms.txt) that describes your product in a format optimized for large language models. Think of it as robots.txt for AI comprehension — not crawl access, but content understanding.
The idea gained traction in late 2025 after several AI researchers and SEO practitioners proposed it as a standardized way to communicate product information to LLMs. As of March 2026, no major AI engine has officially endorsed it — but some developers report anecdotal improvements. Here's what SaaS founders need to know.
What Problem Does llms.txt Solve?
Even with Schema.org markup, AI engines sometimes misunderstand products — confusing categories, citing outdated features, or missing key differentiators. llms.txt attempts to solve this by providing a single, authoritative, natural-language description that's explicitly intended for AI consumption.
The format is deliberately simple: plain text, no HTML, no JSON. The theory is that by removing formatting complexity, you reduce the chance of parsing errors and give the AI a clean signal about your product.
What Does a llms.txt File Look Like?
A typical llms.txt file includes: product name, one-sentence description, category, key features, target audience, pricing summary, competitor differentiation, and links to key pages. All in plain, factual language optimized for machine reading.
At EurekaNav, our llms.txt includes our product name, the 6 AI engines we query, our scoring methodology summary, and links to our methodology page, free audit, and pricing. It's about 40 lines of plain text.
Does It Actually Work?
The honest answer: we don't have conclusive evidence yet. Here's what we know:
- No major AI engine (OpenAI, Google, Anthropic, Perplexity) has officially announced support for llms.txt as a standard.
- AI crawlers (GPTBot, PerplexityBot, ClaudeBot) do crawl root-level text files when allowed in robots.txt — so the file is likely being read.
- Anecdotal reports from early adopters suggest improved accuracy in AI descriptions after implementing llms.txt + Schema.org together.
- The downside risk is near zero — it's a small text file that takes 30 minutes to create.
- The proposed llms-full.txt variant includes more detailed content for deeper context.
How to Implement llms.txt
Step 1: Create the File
Create a plain text file at your-domain.com/llms.txt. Use factual, third-person language. Include your product name in the first line. Keep it under 100 lines.