Serve Markdown to AI Agents (10x Smaller Payloads)

#webdev #ai #productivity #tutorial

Guillermo Rauch shared that Vercel's changelog now serves markdown when agents request it. Same URL, different Accept header.

The insight isn't the size reduction - it's that an entire infrastructure layer (CSS, JS, frameworks) is becoming optional for a growing class of consumers.

How it works

HTTP content negotiation. Browsers send Accept: text/html. Agents can send Accept: text/markdown. Same URL, different representation.

I added this to my Hugo blog. The config:

[outputs]
page = ['HTML', 'MARKDOWN']

[outputFormats.MARKDOWN]
baseName = 'index'
mediaType = 'text/markdown'
isPlainText = true

The middleware (Vercel Edge):

export const config = { matcher: ['/', '/posts/:path*'] }

export default async function middleware(request) {
  if (request.headers.get('accept')?.includes('text/markdown')) {
    const url = new URL(request.url)
    url.pathname = url.pathname.replace(/\/?$/, '/index.md')
    return fetch(url)
  }
}

Test it:

curl -H 'Accept: text/markdown' https://evoleinik.com/posts/markdown-for-agents/

My posts go from ~20kb HTML to ~2kb markdown. Not 250x like Vercel's changelog, but 10x adds up.

The tradeoff

You maintain two output formats. For static sites like Hugo, this is trivial - markdown is the source anyway. For dynamic content or SPAs, it's harder. You'd need to generate markdown server-side or maintain parallel content.