Revalidating Server Content

This is a server-rendered page. The date it was last dynamically-rendered is shown above.

Response headers

This page was rendered with the following headers:

{
  "Cache-Control": "public, max-age=0, must-revalidate",
  "Netlify-CDN-Cache-Control": "public, max-age=31536000, must-revalidate, durable",
  "Cache-Tag": "blog,blog-post:dbae7f7,southeast-asia,south-asia"
}

This gets interpreted differently by the browser and CDN:

• Browsers: a non-cacheable page, must be revalidated on every request
• CDN: cacheable for up to a year, though it will be automatically purged and revalidated on new deployments by default

Cache tags

The Cache-Tag header, in tandem with the purge API, allows a developer to invalidate any content at will (pages, JSON responses, etc.) based on the tags associated with them.

Whenever you purge content for a given tag, all content associated with that tag gets purged. In the example above, you could:

• set the blog tag on all blog posts, allowing you to purge the entire blog at once
• set a unique blog:[id] tag on each blog post, allowing you to purge a single blog post
• set a tag by region on all pages, allowing you to purge all content for a region at once

Tags are completely up to you to decide on, and allow for powerful caching patterns.

Stale-While-Revalidate

In real-world applications, you may want to use stale-while-revalidate as well, so that end-users don’t experience a performance hit as pages are being rebuilt.

Durable Cache

By default, when setting Cache-Control headers on SSR responses, each node in the Netlify CDN’s global edge network will have its own, independent local cache. This can result in inconsistent responses being served to your users.

If you add the durable directive (as on this very page), cache responses become globally consistent.