Up And Running On Vercel

This section of the vercel.json configuration file sets up HTTP response headers for your Vercel deployment, specifically controlling how browsers and CDNs cache your website's content. Here's what each part does:

First Header Rule:

json

CopyInsert
{
  "source": "/(.*)",
  "headers": [
    {
      "key": "Cache-Control",
      "value": "public, max-age=0, must-revalidate"
    }
  ]
}

Applies to all URLs (/(.*)) Sets Cache-Control: public, max-age=0, must-revalidate This means: public: The response can be cached by browsers and CDNs max-age=0: The cache is considered stale immediately must-revalidate: The browser must validate with the server before using a cached version Essentially, this forces the browser to check with the server for fresh content on every request Second Header Rule:

json

CopyInsert
{
  "source": "/_astro/(.*)",
  "headers": [
    {
      "key": "Cache-Control",
      "value": "public, max-age=31536000, immutable"
    }
  ]
}

Applies specifically to files in the /_astro/ path (Astro's build output) Sets Cache-Control: public, max-age=31536000, immutable This means: public: Can be cached by browsers and CDNs max-age=31536000: Cache for 1 year (in seconds) immutable: The content will never change, so browsers can use the cached version without checking for updates This is highly efficient for static assets that get unique filenames when their content changes (which Astro does automatically) The combination of these rules creates an optimal caching strategy:

Static assets (JS, CSS, images) are cached aggressively HTML pages are always validated fresh When you redeploy, browsers will get fresh HTML but can use cached assets until they change This setup balances performance (fast page loads from cache) with freshness (users always see up-to-date content).