AlabJS can emit CDN-ready cache headers for any page without a reverse-proxy config file or platform-specific workarounds. Export cdnCache from a page and AlabJS sets the right headers for Cloudflare, Fastly, or any standard CDN automatically.

Basic usage

// app/blog/page.tsx
import type { CdnCache } from "alabjs";

export const cdnCache: CdnCache = {
  maxAge: 3600, // Cache at the edge for 1 hour
};

export const ssr = true;

export default function BlogPage() {
  return <h1>Blog</h1>;
}

This sets Cache-Control: public, s-maxage=3600 on every response, telling any CDN (Cloudflare, Fastly, Varnish, CloudFront) to cache the page at the edge.

Stale-while-revalidate

Add swr to allow serving stale content while the CDN fetches a fresh copy in the background:

export const cdnCache: CdnCache = {
  maxAge: 3600,
  swr: 600, // Serve stale for up to 10 minutes while revalidating
};

This emits Cache-Control: public, s-maxage=3600, stale-while-revalidate=600.

Cache tags

Tag a response so you can purge a group of pages at once — for example, all blog posts when an author updates their profile:

export const cdnCache: CdnCache = {
  maxAge: 86400,
  tags: ["blog", "author-42"],
};

Tags are sent as Cache-Tag (Cloudflare) or Surrogate-Key (Fastly) depending on your configured CDN provider.

Programmatic tag purge

Call revalidateTag from a server function to purge all pages sharing a tag:

import { defineServerFn } from "alabjs/server";
import { revalidateTag } from "alabjs/cache";

export const publishPost = defineServerFn(async ({ id, authorId }) => {
  await db.posts.update({ where: { id }, data: { published: true } });

  // Purge all CDN edges that cached pages tagged with these values
  await revalidateTag({ tags: ["blog", `author-${authorId}`] });
});

AlabJS calls the CDN purge API automatically (Cloudflare or Fastly) based on your ALAB_CDN environment variable. If no CDN is configured, the call is a no-op.

CDN provider configuration

Set the ALAB_CDN environment variable to enable provider-specific headers and purge APIs.

Cloudflare

ALAB_CDN=cloudflare
CLOUDFLARE_ZONE_ID=your-zone-id
CLOUDFLARE_API_TOKEN=your-api-token

AlabJS emits:

• CDN-Cache-Control: public, max-age=N — Cloudflare-specific TTL (bypasses browser cache)
• Cache-Tag: tag1,tag2 — for tag-based purge

Purge endpoint called: DELETE https://api.cloudflare.com/client/v4/zones/{zone}/purge_cache

Fastly

ALAB_CDN=fastly
FASTLY_SERVICE_ID=your-service-id
FASTLY_API_TOKEN=your-api-token

AlabJS emits:

• Surrogate-Control: max-age=N — Fastly-specific TTL
• Surrogate-Key: tag1 tag2 — space-separated, for tag-based purge

Purge endpoint called: POST https://api.fastly.com/service/{service}/purge

Generic CDN / no config

Without ALAB_CDN, AlabJS emits only the standard header:

Cache-Control: public, s-maxage=N, stale-while-revalidate=M

This works with any CDN that respects Cache-Control.

CSRF and public pages

Pages with cdnCache are treated as public — AlabJS skips CSRF cookie injection for them. This is intentional: a shared CDN cache would deliver the same CSRF token to every visitor, defeating CSRF protection.

If a page needs both CDN caching and authenticated forms, split the authenticated form into a <Dynamic> section (loaded client-side) and cache only the public shell.

Environment variables

Variable	Required	Description
ALAB_CDN	No	CDN provider: cloudflare or fastly. Unset = generic.
CLOUDFLARE_ZONE_ID	Cloudflare	Zone ID from the Cloudflare dashboard.
CLOUDFLARE_API_TOKEN	Cloudflare	API token with Cache Purge permission.
FASTLY_SERVICE_ID	Fastly	Service ID from the Fastly dashboard.
FASTLY_API_TOKEN	Fastly	API token with purge permission.

API Reference

export const cdnCache: CdnCache

Page-level export. Enables CDN cache headers for this page.

import type { CdnCache } from "alabjs";

interface CdnCache {
  /** Shared cache TTL in seconds (sets s-maxage). */
  maxAge: number;
  /** Stale-while-revalidate window in seconds. */
  swr?: number;
  /** Cache tags for group purge. */
  tags?: string[];
}

revalidateTag({ tags }): Promise<void>

Purges all CDN edges that cached responses tagged with any of the given tags. Fire-and-forget safe — errors are logged but do not throw.

import { revalidateTag } from "alabjs/cache";

revalidatePath(path): void

Removes the in-process ISR cache for path. For full edge purge, use revalidateTag with a matching tag on the page.

See Cache & ISR for ISR-specific documentation.