Adding an llms.txt file to Hugo

Today, I set out to add an llms.txt to this site. I’ve made a few similar additions in the past with raw post markdown files and a search index. Every time I try and change something with outputFormats in Hugo, I forget one of the steps, so in writing this up, finally I’ll have it for next time.

Steps

First, I added a new output format in my config.toml file:

[outputFormats.TXT]
mediaType = "text/plain"
baseName = "llms"
isPlainText = true

Then, I added this format to my home outputs:

[outputs]
home = ["HTML", "RSS", "JSON", "SearchIndex", "TXT"]

Finally, I created a template file at layouts/_default/index.txt that renders my site content in a structured markdown per the spec recommendations.

# {{ .Site.Title }}

> {{ .Site.Params.description }}

## Content
{{ range $type := .Site.Params.front_page_content }}
### {{ title $type }}

{{ range (where $.Site.RegularPages "Type" $type) }}- [{{ .Title }}]({{ .Permalink }}index.md): Published {{ .Date.Format "2006-01-02" }}
{{ end }}{{ end }}

Now, when I build my site, it generates an llms.txt file at the root that contains a Markdown list of the content on this site. This makes it easy for language models to understand my site without dealing with HTML markup.