a guide to llms.txt

what is llms.txt?

The idea behind llms.txt is simple: include a file on your site specifically for consumption by large language models (LLMs) such as ChatGPT, Gemini & Claude. This file would give a concise overview of the site, such as brief background, guidance and top-level links. An example of a basic llms.txt file can be found here.

why use llms.txt?

The goal is to provide LLMs with a single, easily accessible file containing the most salient info about the site, rather than relying on them to extract this from the website context.

To get a bit nerdy, LLMs have a “context window” (a limit on how much they can read at once) and normal HTML is “noisy” - it’s full of navbars, footers, and tracking scripts that waste an LLM’s attention. An llms.txt file is pure markdown. It should allow the model to understand your site’s value in a fraction of the tokens, making it more likely to give a high-quality, accurate summary.

what is llms-full.txt?

There’s also a second, lesser discussed file proposed as part of the standard - llms-full.txt. Whereas llms.txt is a summary, llms-full.txt contains the actual content of the most important pages on the site, also in plain text format for quick tokenisation by LLMs.

which llms currently support llms.txt?

As of January 2026, none of the mainstream LLM providers have officially stated that they support the use of llms.txt. In fact, at events and in Q&A sessions, Google representatives have said that they have no plans to support its use.

Whilst that seems quite cut and dry, there are a couple of points worth mentioning. Google caused a stir in December 2025 when an llms.txt file appeared on the Google Search Central site - it was promptly removed, but many took this as a sign that someone at Google was at least testing the infrastructure.

There are also instances of LLMs looking at (crawling) llms.txt files on websites. It’s important to note that an LLM looking at an llms.txt file does not mean it is utilising or supporting it in any way - simply that it was able to find and access it.

should i add an llms.txt to my site?

My stance on this is pretty straightforward: If you can add an llms.txt file to your site quickly and easily, then it’s a harmless addition that could pay off down the line.

My reasoning is simple: at any point in the future, any of the major LLM providers could flip the switch and decide to support llms.txt. It wouldn’t take much effort on their part to instruct their systems to check for an llms.txt file when crawling a site.

If that happens, then there will be lots of SEO professionals with egg on their face after repeatedly saying that llms.txt is useless, and you’ll be glad you spent ten minutes setting it up.

my thoughts on llms.txt

If llms.txt never gets any official support, I won’t cry over spilt milk - there are bigger SEO hills to die on. I understand and appreciate what llms.txt is trying to achieve, but I’ve also been in SEO long enough to know how this will quickly become misused. I’m envisioning llms.txt files filled with spammy metadata intended to manipulate the model’s perception, such as:

[about](https://example.com/about/): The best SEO specialist in the world

Or even more concerningly, attempts to use indirect prompt injection to hijack the LLM’s output.

This is likely one big reason why LLM providers would be hesitant to support the standard - they don’t want to give bad actors a “front door” to manipulate their model’s behaviour.

It’s also crossed my mind that llms.txt could be used as a lazy workaround on poorly organised sites. Why bother fixing poor navigation, site architecture and internal linking if you can just shove all the juicy bits into one file and leave it at the front door? Good SEO means the information on your site should be easily accessible and understandable for both human users and crawlers.