llms.txt explained (with a template)

llms.txt is a plain-text file you put at the root of your website, like robots.txt, that gives AI systems a concise, curated description of your site and links to the pages that matter. It was proposed by Jeremy Howard of Answer.AI in September 2024 and has since been adopted by thousands of sites, mostly documentation and developer tools, and increasingly by ordinary businesses.

This post explains what it is, what to expect from it, and gives you a template.

The problem it solves

Language models have small context windows compared with the size of a website, and most of a page's HTML is navigation, scripts and styling rather than content. When an assistant fetches your homepage to answer a question, it may get a few thousand tokens of menus and cookie banners before any useful text.

llms.txt offers a shortcut: one Markdown file, written for machines, that says who you are, what you do, and where the authoritative pages are. The companion convention llms-full.txt holds the full text of those key pages in one file so a model can read everything in a single fetch.

What it is not

Be realistic. As of 2026 no major provider has committed to reading llms.txt in the way search engines read robots.txt or sitemaps. Evidence that it directly changes AI answers is thin. Treat it as:

• A cheap, harmless improvement that may help agents and retrieval tools that do look for it.
• A useful exercise: writing a clear 300-word description of your business is exactly the entity clarity that GEO depends on, and you should reuse that text in your About page, Organization schema and directory profiles.
• A signal of care that some tools and auditors (including Seoptist) check for.

It is not a replacement for structured data, a sitemap, or readable service pages, and it does not control crawling; robots.txt does that.

The format

The specification is deliberately simple Markdown:

1. An H1 with the site or business name (required).
2. A blockquote with a one-paragraph summary.
3. Optional paragraphs with important context.
4. H2 sections containing lists of links, each as [title](url): description.
5. An optional ## Optional section for links a model can skip when context is tight.

Keep it under about 2,000 words. Use absolute URLs. Write in plain language; this is not the place for slogans.

A template for a UK business

Replace the bracketed parts and delete sections you do not need.

# [Business name]

> [Business name] is a [what you are] in [town or region], serving [who] with [core services]. Established [year]. [One differentiator in plain terms.]

Key facts:
- Location: [address], [postcode]. Service area: [towns/counties].
- Contact: [phone], [email]. Hours: [hours].
- Accreditations: [e.g. Gas Safe registered, SRA regulated, ISO 9001].
- Pricing: [e.g. from £X; free quotes; fixed fees].

## Services
- [Service one](https://www.example.co.uk/services/one/): [one sentence on what it is and who it is for].
- [Service two](https://www.example.co.uk/services/two/): [one sentence].

## About
- [About us](https://www.example.co.uk/about/): history, team and accreditations.
- [Reviews](https://www.example.co.uk/reviews/): verified customer reviews.
- [Areas we cover](https://www.example.co.uk/areas/): towns and postcodes served.

## Help and policies
- [FAQ](https://www.example.co.uk/faq/): answers to common questions about pricing, timings and guarantees.
- [Contact](https://www.example.co.uk/contact/): phone, email and booking form.

## Optional
- [Blog](https://www.example.co.uk/blog/): guides and news.
- [Terms](https://www.example.co.uk/terms/): terms of business.

Save it as llms.txt at the root of the site so it is reachable at https://www.example.co.uk/llms.txt, served as text/plain or text/markdown. You can see Seoptist's own at /llms.txt.

Writing tips

• Lead with the facts a customer or model would need to recommend you: what, where, for whom, since when, and any regulatory status. Models weigh verifiable, specific claims.
• Keep names consistent with your website, Google Business Profile and Companies House entry. "Smith & Sons Plumbing Ltd" and "Smiths Plumbers" look like two businesses.
• Describe services in the words customers use, not internal jargon. "Boiler repair" rather than "heating system remediation".
• Update it when things change, and date it in a comment if you like. Stale prices or an old address undermine trust.
• Do not include anything you would not put on a public page. The file is public.

Checking it

Fetch the URL in a browser to confirm it is served as plain text, not redirected to a 404 page or an HTML template. Run it through a Markdown linter if you want to be tidy. Then add it to your GEO checklist and move on to the things with more leverage: crawler access, structured data and answer-shaped content.

Seoptist generates an llms.txt for you from your business profile and audit, and flags it when it is missing, unreachable or out of date.