Why Your Micro-SaaS Needs an llms.txt File (And How to Generate One)

llms.txt is the emerging standard for AI-readable websites. Learn what it is, why it matters for GEO, and how to generate one automatically at build time.

Why Your Micro-SaaS Needs an llms.txt File

You have a robots.txt for Google. You need an llms.txt for the AI.

What Is llms.txt?

llms.txt is a plain-text file at your site root that gives generative engines a curated map of your content — what each page is, what it answers, and where to find it. It is to AI crawlers what sitemap.xml is to search engines: a hint, not a guarantee, but a strong one.

The format is markdown:

code

# Project Name

> Short description of the project.

## Docs

- [Getting Started](https://example.com/start): Setup guide

- [API Reference](https://example.com/api): Endpoint docs

## Changelog

- [v1.0.0](https://example.com/changelog#v1): Initial release

Why It Matters for GEO

Generative engines do not crawl every link. They prioritize sources that are easy to ingest and clearly structured. llms.txt does three things:

Signals freshness — a dated, maintained file tells the model the site is active.
Disambiguates entities — consistent naming across the file builds a clean entity graph.
Surfaces the right pages — you control which pages the model reads first.

Without it, the model falls back to whatever it can scrape — often your terms of service or a stale blog post.

llms.txt vs robots.txt vs sitemap.xml

File	Audience	Purpose
`robots.txt`	Search crawlers	Allow/deny crawling
`sitemap.xml`	Search engines	List all URLs + priority
`llms.txt`	Generative engines	Curated, described content map

They complement each other. You want all three.

How to Generate One at Build Time

Hand-maintaining llms.txt drifts. Generate it from the same source of truth as your sitemap — your route config.

In SpaceZero, llms.txt and llms-full.txt are generated by the llmsTxtPlugin in vite.config.ts from SITEMAP_ROUTES and CHANGELOG_ENTRIES:

typescript

// vite.config.ts — runs on every build

const llmsTxt = `# ${appName}

${appDescription}

## Documentation

${SITEMAP_ROUTES.map((r) => `- [${r.path}](${appUrl}${r.path})`).join('\n')}

## Changelog

${CHANGELOG_ENTRIES.map((e) => `- [${e.version}](${e.url}) - ${e.title}`).join('\n')}

Because it is generated from the same config that builds your sitemap and RSS, it can never drift out of sync.

The Two-File Pattern

File	Length	Purpose
`llms.txt`	Short	Concise map for quick ingestion
`llms-full.txt`	Long	Full documentation for deep context

Ship both. The short file gets cited; the long file gets read.

What to Put In It

A one-line description of what the product does.
The core pages a new visitor needs (home, pricing, docs, support).
The API surface, if you have one.
A dated changelog.

What to Leave Out

Legal boilerplate.
Every blog post ever written.
Marketing fluff that does not answer a question.

The rule: if a page would not help an AI answer a user's question, it does not belong in llms.txt.

The Bottom Line

llms.txt is cheap to generate, impossible to maintain by hand at scale, and increasingly the difference between being cited and being invisible. If your build does not emit one, add it this week.