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llms.txt for Express.js

Express is the most popular Node.js web framework. Serving llms.txt is trivial — either via express.static() for a static file or a dedicated GET route for dynamic generation.

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Option 1: static file with express.static()

If your app already uses express.static() to serve a public/ folder, simply drop llms.txt into that folder. Express will serve it at /llms.txt with no additional code.

server.js — static file approach 
// server.js
const express = require('express');
const app = express();

// Serve everything in ./public/ at the root URL.
// If public/llms.txt exists, it is available at /llms.txt automatically.
app.use(express.static('public'));

app.listen(3000, () => console.log('Listening on http://localhost:3000'));

// Project structure:
// your-express-app/
// ├── public/
// │   └── llms.txt   ← add this
// └── server.js

Express automatically sets the Content-Type to text/plain for .txt files served via express.static(). To add a Cache-Control header, pass maxAge in the static options:

Cache-Control with express.static() 
app.use(express.static('public', { maxAge: '1h' }));

Option 2: dedicated GET route

For full control over headers and content, add a dedicated route. This is also the right approach when the content is generated at runtime from a database or your API route registry.

server.js — GET route 
// server.js — dedicated GET route
const express = require('express');
const app = express();

const llmsContent = `# Your Site

> One-sentence description of what your site or product does.

## Documentation

- [Getting Started](https://yoursite.com/docs/start): Install and configure in minutes.
- [API Reference](https://yoursite.com/docs/api): Full endpoint catalog with examples.

## Product

- [Overview](https://yoursite.com/product): Core features and capabilities.
- [Pricing](https://yoursite.com/pricing): Plans and billing details.

## Optional

- [Changelog](https://yoursite.com/changelog): Release history.
- [GitHub](https://github.com/your-org/your-repo): Source code.
`;

app.get('/llms.txt', (req, res) => {
  res.type('text/plain');
  res.set('Cache-Control', 'public, max-age=3600, stale-while-revalidate=86400');
  res.send(llmsContent);
});

app.listen(3000);

Place this route before any catch-all route handlers or 404 middleware, otherwise Express will never reach it.

TypeScript version

If your project uses TypeScript with @types/express, type the handler parameters explicitly to avoid implicit any errors:

server.ts — TypeScript 
// server.ts — TypeScript version with typed Request/Response
import express, { Request, Response } from 'express';

const app = express();

const llmsContent = `# Your Site

> One-sentence description of your product or service.

## Documentation

- [Getting Started](https://yoursite.com/docs/start): Quick setup guide.
- [API Reference](https://yoursite.com/docs/api): Full endpoint catalog.

## Optional

- [Changelog](https://yoursite.com/changelog): Release history.
`;

app.get('/llms.txt', (req: Request, res: Response): void => {
  res.set({
    'Content-Type': 'text/plain; charset=utf-8',
    'Cache-Control': 'public, max-age=3600, stale-while-revalidate=86400',
  });
  res.send(llmsContent);
});

app.listen(3000, () => console.log('Server running on http://localhost:3000'));

Dynamic generation from routes metadata

For larger applications, maintain a publicRoutes array alongside your route definitions. The /llms.txt handler maps this array to Markdown links — ensuring the file stays in sync with your actual routes.

server.js — dynamic generation 
// server.js — generate llms.txt dynamically from route metadata
const express = require('express');
const app = express();

// Define your public routes with metadata
const publicRoutes = [
  { title: 'Getting Started', path: '/docs/start', description: 'Install and configure in minutes.' },
  { title: 'API Reference', path: '/docs/api', description: 'Full endpoint catalog with examples.' },
  { title: 'Authentication', path: '/docs/auth', description: 'OAuth 2.0 and API key setup.' },
  { title: 'Webhooks', path: '/docs/webhooks', description: 'Event payloads and retry policy.' },
  { title: 'Pricing', path: '/pricing', description: 'Plans and billing details.' },
];

const SITE_URL = process.env.SITE_URL || 'https://yoursite.com';

app.get('/llms.txt', (req, res) => {
  const links = publicRoutes
    .map((r) => `- [${r.title}](${SITE_URL}${r.path}): ${r.description}`)
    .join('\n');

  const body = [
    '# Your Site',
    '',
    '> One-sentence description of your product.',
    '',
    '## Documentation',
    '',
    links,
  ].join('\n');

  res.set({
    'Content-Type': 'text/plain; charset=utf-8',
    'Cache-Control': 'public, max-age=3600, stale-while-revalidate=86400',
  });
  res.send(body);
});

app.listen(3000);

Set SITE_URL as an environment variable so the same code works across local, staging, and production environments.

Cache-Control header

Always add a Cache-Control header. A one-hour TTL with stale-while-revalidate is a sensible default — it allows reverse proxies and CDNs (nginx, Cloudflare, AWS CloudFront) to cache the response and serve stale content while revalidating in the background:

Recommended Cache-Control 
res.set('Cache-Control', 'public, max-age=3600, stale-while-revalidate=86400');

If you use a CDN in front of Express, check that the CDN respects Cache-Control from the origin. Cloudflare honors it by default; AWS CloudFront requires a cache policy that allows origin headers to pass through.

Verify

After starting your server, confirm the file is served correctly:

Local verification 
# Check headers
curl -I http://localhost:3000/llms.txt
# Expected:
# HTTP/1.1 200 OK
# Content-Type: text/plain; charset=utf-8
# Cache-Control: public, max-age=3600

# Check content
curl http://localhost:3000/llms.txt | head -5
# Should print:  # Your Site

After deploying, run the same check against your live URL, then paste it into the llms.txt validator for full spec compliance.

Checklist before shipping

  • File served at /llms.txt with 200 OK.
  • Content-Type: text/plain; charset=utf-8 is set.
  • Cache-Control header is present.
  • Exactly one H1 heading at the top of the file.
  • Blockquote summary immediately after the H1.
  • All URLs are absolute (https://).
  • Route is registered before any catch-all or 404 handlers.
  • Validator returns no errors: llmtxt.info/validator/

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