HTTP caching for https://en.wikipedia.org

Overview

✅

This resource can be cached.

This response can be cached because of a directive in the Cache-Control header.

✅

This resource has a cache control header.

Cache-Control: private, s-maxage=0, max-age=0, must-revalidate, no-transform
❌

This resource does not have an entity tag.

HTTP response cache headers

These are the raw caching-related HTTP headers that were returned by the server:
age: 5239
cache-control: private, s-maxage=0, max-age=0, must-revalidate, no-transform
last-modified: Thu, 21 Nov 2024 05:04:09 GMT
vary: Accept-Encoding,Cookie,Authorization
🧭

Cache-Control

Cache-Control: private, s-maxage=0, max-age=0, must-revalidate, no-transform
  • 🔒
    Private
    (RFC)
    The private directive indicates that the response is intended only for a single user and must not be stored in any shared cache. Typically, this means that the response will only be stored in the browser cache.
  • ⏳
    Max Age
    (RFC)

    The max-age directive indicates the response should be considered stale immediately.

    For example, since this response was fetched on Nov 21, 2024, 6:31:30 AM, it will become stale on Nov 21, 2024, 6:31:30 AM.

  • ⌛
    Shared Max Age
    (RFC)

    The s-maxage directive indicates the response should be considered stale by shared caches (such as a CDN) immediately.

    For example, since this response was fetched on Nov 21, 2024, 6:31:30 AM, it will become stale for shared caches on Nov 21, 2024, 6:31:30 AM.

  • ✨
    No Transform
    (RFC)
    The no-transform directive indicates that any intermediate cache must not transform this response (for example: change content type, compress data, filter responses, etc.)
  • ❗
    Must Revalidate
    (RFC)
    The must-revalidate directive indicates that when the response becomes stale, the cache must revalidate the cached response before it can be used again.
⌛

Age

The Age header indicates how long the response has been in the cache.

Age: 5239

In this case, the response has been in the cache for 5239 seconds (1 hour 27 minutes 19 seconds).

🕒

Last Modified

The Last-Modified header indicates the last time the resource was modified on the origin server.

Last-Modified: Thu, 21 Nov 2024 05:04:09 GMT

In this case, the resource was last modified on Nov 21, 2024, 5:04:09 AM (about 1 hour ago).

🔀

Vary

The Vary header indicates which request headers the server response may be dependent on. If any of the listed headers change, then the response may be different. This allows the server to send the correct cached response for each request. For example, ensuring that a client that does not support compression does not receive a cached compressed response.

Vary: Accept-Encoding,Cookie,Authorization

Accept-Encoding: The server response is expected to be different depending on the encodings that the client accepts via the Accept-Encoding header in the request. For example, if the client does not support compression, then the server may send a cached uncompressed response. If the client does support compression, for example, by sending a a Accept-Encoding: gzip header, then the server may send a cached compressed response.

Cookie: The server response will depend on the cookies that the client sends in the request. Typically, this means that the server will cache authenticated responses (since authenticated responses typically include a cookie), but the cached pages will only be served to the same client that sent the request.