What is llms.txt and why does your HubSpot site need one?

What is llms.txt?

llms.txt is an emerging standard — proposed by fast.ai founder Jeremy Howard — that gives AI language models a structured index of your website's content. It lives at /llms.txt on your domain, just like robots.txt or sitemap.xml.

The file is plain text and follows a simple format: a title, an optional description, and a list of links to your key pages organised into sections. AI tools that support the standard can read this file to understand what your site contains and reference the right pages when answering relevant questions.

Why does it matter for HubSpot users?

If you run your website on HubSpot, you're probably publishing pages, blog posts, and landing pages regularly. Without an llms.txt file, AI tools have no easy way to discover all of that content — they might know about a few pages they've crawled, but they won't have a complete picture.

With an llms.txt file in place, you're giving AI tools a clean, structured list of everything you've published. When someone asks ChatGPT or Perplexity a question your content answers, there's a much better chance your site gets cited.

Which AI tools support llms.txt?

The standard is still being adopted, but it's growing fast. Tools and platforms that have announced support or are actively crawling llms.txt files include Perplexity, Claude, and a number of AI-powered search tools. As the standard matures, broader support across ChatGPT and others is expected.

Even if only a handful of tools support it today, the cost of adding an llms.txt file is essentially zero — and the upside as adoption grows is significant.

How is it different from a sitemap?

A sitemap tells search engine crawlers where all your pages are. llms.txt is designed for AI language models — it's human-readable, prioritises your most important content, and includes descriptive context rather than just a list of URLs. Think of it as a curated guide to your site rather than an exhaustive technical index.

How do you add llms.txt to HubSpot?

HubSpot doesn't natively support llms.txt — you can't just drop a file in a folder the way you can on a traditional web server. The options are either creating and maintaining a static file manually, or using an app that generates and serves it automatically.

We cover both approaches in detail in our guide: How to add llms.txt to your HubSpot website →