What is llms.txt?
It's a short Markdown file at the root of your site, at /llms.txt, that tells AI tools what your site is and where the useful pages are.
Think of it as a cover note for machines. A person visiting your site gets the design, menus and images. A language model reading llms.txt gets a clean summary: your name, a short description, and a list of links to the pages that matter, each with a line saying what's there.
The idea was proposed in September 2024 by Jeremy Howard of Answer.AI, and the format is published at llmstxt.org. It's an open proposal rather than an official standard. Nobody has to support it, and nothing checks it.
What goes in an llms.txt file?
A title, a short summary and lists of links. Only the title is required. There's a short example further down this page.
- An H1 with the name of the site or business. This is the only required part.
- A blockquote with a short summary: what you do, who for and where.
- Optional paragraphs or bullet points with key facts.
- H2 sections, each a list of Markdown links with a short note on what each page covers.
- A section headed "Optional" for links a tool can skip when it's short of space.
Does llms.txt help you rank or get recommended?
Not directly. It isn't a ranking factor in Google or Bing, and none of the major AI assistants has said it reads llms.txt when it answers a question.
ChatGPT, Claude, Gemini and Perplexity find businesses by searching and reading pages. They don't need an llms.txt to do that, and a good one won't make up for unclear service pages, missing prices or a blocked crawler.
Where it does help is with tools that look for it. Its clearest use today is in developer tools, where people point an AI coding assistant at a project's llms.txt to load its documentation. Some AI tools and agents check for one when they visit a site, so it's a small bet that costs very little.
Is llms.txt the same as robots.txt?
No. robots.txt tells crawlers what they may and may not fetch. llms.txt only describes your site. It can't block or allow anything.
If you want to control which AI crawlers read your site, that's still done in robots.txt, using names such as OAI-SearchBot, GPTBot, Claude-SearchBot and Google-Extended. An llms.txt file is only read, if at all, once a tool has been let in.
What's in Foundry's own llms.txt?
Our file at foundryagency.co.uk/llms.txt sums up the business in plain text, and points to a longer file at /llms-full.txt with the detail. Both are generated from the same content files as the website, so they can't drift out of date.
The short file opens with our name and a one-sentence description of what we do. Then come our key facts: who runs the business, the team, our address, phone and email, the areas we serve, our averages, our website price, how to start, and our headline client results. Under that sit sections for each service group, with a link and a one-line description for every service, then our case studies, area pages, company pages and an optional section.
The full file repeats those facts, then goes through every service, area and case study page in turn: its heading, URL, summary, At a glance facts and FAQs. llms-full.txt is a common companion that many sites use, though it isn't part of the original proposal. Anything we haven't confirmed is left out of both files, the same rule as the website.
Does your site need an llms.txt?
It's worth adding if you can keep it accurate. It isn't worth paying for on its own, and it's never a priority over clear pages.
Add one if you have documentation, a product people build on, or a lot of pages where the useful ones are hard to spot. For a small service business, a short file with your facts and main pages is plenty. The bigger risk is a file that goes stale: if it lists an old service or a closed office, it's worse than none. That's why ours is generated, not written by hand.
How do you write an llms.txt, step by step?
Six steps, about an hour for most small sites.
- Write a short description of the business: what you do, who for, where, and how to start.
- List your key facts as short bullet points: services, areas, "from" prices where you have them, turnaround and contact details.
- Pick the pages that matter: services, pricing, case studies, about and contact. Skip archives, tag pages and anything thin.
- Write a Markdown link for each, with a short note on what the page covers, grouped under H2 headings.
- Save it as plain text at the root of your site, so it loads at yourdomain.co.uk/llms.txt.
- Check it whenever prices, services or contact details change, or generate it from your content so it updates itself.