What is llms.txt — and does your business need one?

llms.txt is a plain-text file on your website that gives AI assistants like ChatGPT, Claude and Perplexity a clean, structured summary of who you are, what you do, and where your key pages are. It is a front-door briefing for those assistants rather than for Google, which has confirmed its own Search ignores the file. The benefit with other assistants is plausible but unproven; the cost is about half an hour.

Why it exists

A growing share of your potential customers no longer start at Google's blue links. They ask an AI assistant: "who's a good SEO consultant in Cardiff?", "recommend a family solicitor near Swansea". The assistant answers by drawing on websites it can read and trust. Websites are built for humans, though — full of navigation, pop-ups and marketing copy that make the underlying facts hard for a machine to extract reliably.

llms.txt, proposed in 2024, tries to solve this the way robots.txt solved crawler instructions thirty years ago: a simple, predictable file at a standard address (yourdomain.co.uk/llms.txt), written in Markdown, that an AI system can find and parse in one pass. Uptake since then has been patchy, and the major platforms have stayed quiet about whether they use it.

What goes in one

A good llms.txt is short and factual: your business name, a one-paragraph description, your key services, coverage area, contact details, and an annotated list of your most important pages. Here's a trimmed version of the one on this site:

# Webolific

> Independent SEO consultancy based in South Wales, UK.
> Helps businesses in Cardiff, Newport and Swansea improve
> visibility in Google and AI-powered search.

## Key pages
- [SEO Cardiff](https://webolific.co.uk/cardiff-seo-services/):
  SEO services for Cardiff businesses, with pricing and FAQ

## Facts
- Independent consultant, not an agency
- No long-term contracts

That's genuinely it. No code, no plugins — a text file uploaded to your web root.

What Google says about llms.txt

Google's guide to AI features in Search states it directly: Google Search does not use llms.txt, and the file will not change how you appear in AI Overviews or AI Mode. Those features run on Google's normal index and ranking systems, so what makes you visible in them is the ordinary work: pages Google can crawl, genuinely helpful content, and business details it can verify.

That leaves llms.txt as a file for the assistants Google's guidance doesn't speak for: ChatGPT, Claude, Perplexity, Copilot. None of them has publicly confirmed using it to rank or cite a business. Some sites publish one anyway, including parts of Anthropic's own documentation, but whether it changes what those tools say about you is untested. Treat it as an experiment, not a lever. For the wider picture of what does move the needle, see what is generative engine optimisation?

Does your business actually need one?

On current evidence it is optional. The trade-off is lopsided, which is the only reason to bother:

• Cost: around thirty minutes once, plus updates when your services change.
• Downside: none. It is invisible to human visitors and cannot affect your Google rankings in either direction.
• Possible upside: if a non-Google assistant does read it, your services, coverage and contact details are stated by you rather than inferred from fragments. Plausible, not promised.

We still add one for local service businesses because it is cheap and cannot backfire. It sits well below the things that actually drive AI visibility, though: pages Google can crawl and index, content that answers real questions with the answer near the top, consistent business details across the web, and a robots.txt that lets AI crawlers in. llms.txt is a small part of AI search optimisation, not the point of it.

How to create yours

1. Write a one-paragraph factual description of your business: what you do, for whom, where.
2. List your 5–10 most important pages with a one-line description of each.
3. Add hard facts an AI should get right: services, coverage area, contact details, anything you're often asked.
4. Save it as llms.txt and upload it to your website's root directory.
5. While you're at it, check your robots.txt isn't blocking AI crawlers like GPTBot and ClaudeBot — many sites block them by accident and wonder why AI never mentions them.

The bigger picture

Whether llms.txt specifically becomes the standard matters less than what it represents: search is splitting into two audiences (human readers and machine readers) and your website now needs to serve both. The businesses that make themselves easy for machines to understand will be the ones AI recommends. The ones that don't will be invisible in a channel their customers are already using.

For the other assistants, see how to get cited by ChatGPT and Perplexity.