Starlight: vendor profile

In short

A default Starlight 0.42.9 build kept its home H1 in the server HTML and wrote a 404.html, but no llms.txt or robots.txt. With no site value set, the sitemap was skipped. Community plugins supply llms.txt and JSON-LD, and Pagefind provides search. The Astro Technology Company, which builds Astro under it, joined Cloudflare on 2026-01-16.

At a glance

standards.txt starlight

llms-txt               = partial
markdown-negotiation   = no statement
markdown-twin          = partial
initial-html           = supports
real-404               = supports
vary-accept            = no statement

2 supports, 2 partial or announced, 2 no statement.

Starlight Framework

Astro's documentation framework that pre-renders pages to static HTML with a built-in 404 page and Pagefind search; sitemap needs the Astro site URL, and llms.txt, .md.txt twins and JSON-LD come from community plugins.

Type: Framework
Operator, as the facts below state it: The Astro Technology Company (part of Cloudflare since January 2026)
Home page: starlight.astro.build, answered HTTP 200 on 2026-11-05
Last read: 5 November 2026

What it does for this layer

Starlight's prerender option defaults to true, so pages are built as static HTML; prerender: false hands them to an SSR adapter instead. [primary source] source, read 5 November 2026.
Starlight injects a default 404 page; disable404Route: true turns that off so a project can ship its own src/pages/404.astro. [primary source] source, read 5 November 2026.
Search in Starlight is Pagefind with no setup step; a page drops out of the index with pagefind: false in its frontmatter. [primary source] source, read 5 November 2026.
Starlight's plugins page lists starlight-llms-txt, a community plugin that adds llms.txt following llmstxt.org. [primary source] source, read 5 November 2026.
The same Starlight plugins list carries starlight-md-txt, which exposes each page as raw Markdown at a .md.txt URL. [primary source] source, read 5 November 2026.
For structured data the Starlight plugins list points to starlight-seo, a community plugin that adds a connected JSON-LD graph and a build-time SEO audit. [primary source] source, read 5 November 2026.
The starlight-llms-txt plugin site says the plugin generates llms.txt, llms-full.txt and llms-small.txt for a Starlight site. [secondary source] source, read 5 November 2026.
starlight.astro.build itself returned 404 for /llms.txt and /robots.txt on 2026-11-05, while /sitemap-index.xml answered 200. [observed] source, read 5 November 2026.
GitHub lists @astrojs/starlight 0.42.9 as released on 2026-11-04 by the astrobot-houston account. [primary source, 2026-11-04] source, read 5 November 2026.
The Astro Technology Company, which builds the Astro framework under Starlight, joined Cloudflare on 2026-01-16 and says Astro stays open source and MIT licensed. [primary source, 2026-01-16] source, read 5 November 2026.
Starlight's getting started page scaffolds a project with npm create astro@latest -- --template starlight. [primary source] source, read 5 November 2026.

Test build

A default Starlight project (npm create astro@5.3.1 -- starlight-test --template starlight --install --no-git --yes --skip-houston; npm run build) with @astrojs/starlight 0.42.9 and astro 7.4.1 skipped the sitemap on 2026-11-05 because site was unset. [observed] source, read 5 November 2026.
The Starlight 0.42.9 build output held 404.html, a pagefind index and the pages, with no llms.txt or robots.txt; the home H1 'Welcome to Starlight' was in the server HTML. [observed] source, read 5 November 2026.
Under astro preview a request for / sending only Accept: text/markdown got 404 text/html instead of the home page, a preview server quirk worth knowing before testing negotiation locally. [observed] source, read 5 November 2026.

Products and plans

Plans and prices as the vendor's own pages showed them on the date read.
Product	What it is	Price	As of	Source
Starlight (@astrojs/starlight)	Astro integration that turns a content folder into a documentation site.	Free, open source MIT licence, free; version 0.42.9 on 2026-11-04	2026-11-05	source

Standards

The six standards this site tracks; no statement means the pages read said nothing.
Standard	Status	What the vendor's pages say	Source
llms-txt	partial	Starlight's own plugins page lists the community plugin starlight-llms-txt for llms.txt; core Starlight writes none.	source
markdown-negotiation	no statement	No statement found in the Starlight configuration reference, customization guide or plugins list; starlight.astro.build returned HTML to Accept: text/markdown.	none
markdown-twin	partial	The community plugin starlight-md-txt, listed by Starlight, exposes pages as Markdown at .md.txt URLs.	source
initial-html	supports	Starlight pages are pre-rendered by default (prerender defaults to true).	source
real-404	supports	Starlight injects a default 404 page unless disable404Route is set, and astro preview returned 404 for a made-up path.	source
vary-accept	no statement	No statement found in the Starlight configuration reference or site search guide; Starlight does not negotiate on Accept.	none

Checks on its own site

Readings of starlight.astro.build, the vendor's own website, which describe that site and not the product.
Reading	Result	Date
Home page request	HTTP 200; H1 in the initial HTML: yes; 537 words; 0 JSON-LD blocks	2026-11-05
Request with Accept: text/markdown	HTTP 200, text/html, Vary: Accept-Encoding	2026-11-05
/llms.txt at the host root	HTTP 404, text/html, 21 KB	2026-11-05
A made-up path	HTTP 404	2026-11-05
Ora score, cached	37, grade D	2026-11-03
Cloudflare keyless scan	7, L0 Not Ready	2026-11-05

What it does not do

Without site set in astro.config.mjs a Starlight build silently skips sitemap generation, as the 0.42.9 test build showed. source, read 5 November 2026.

Related pages on this site

Sources

Starlight: home page https://starlight.astro.build/, read 5 November 2026
Configuration Reference | Starlight https://starlight.astro.build/reference/configuration/, read 5 November 2026
Customizing Starlight | Starlight https://starlight.astro.build/guides/customization/, read 5 November 2026
Site Search | Starlight https://starlight.astro.build/guides/site-search/, read 5 November 2026
Plugins and Integrations | Starlight https://starlight.astro.build/resources/plugins/, read 5 November 2026
starlight-llms-txt documentation https://delucis.github.io/starlight-llms-txt/, read 5 November 2026
Getting Started | Starlight https://starlight.astro.build/getting-started/, read 5 November 2026
Release @astrojs/starlight@0.42.9 · withastro/starlight · GitHub https://github.com/withastro/starlight/releases/tag/%40astrojs/starlight%400.42.9, read 5 November 2026
The Astro Technology Company joins Cloudflare https://astro.build/blog/joining-cloudflare/, read 5 November 2026
Starlight LICENSE https://raw.githubusercontent.com/withastro/starlight/main/LICENSE, read 5 November 2026

Last reviewed 5 November 2026