Dries Buytaert

Explanation

private means the response can only be stored by the browser's cache, but not by CDNs, proxies, or any other shared caches.

The size of the message body, in bytes.

The type of the message body, specified as a MIME type.

A unique identifier that changes every time a page at a given URL changes. It acts as a fingerprint. A cache can compare Etag values to see if the page has changed and became stale. For example, a browsers will send the ETag value of a cached page in an If-None-Match header. The web server compares the ETag value sent by the browser with the ETag value of the current version of the page. If both values are the same, the web server sends back a 304 Not Modified status and no body.

The Vary header specifies a list of headers that must be considered when caching responses. For a cached response to be used, these headers must match between the cached response and the new request. This ensures that the appropriate version of a resource is served based on factors like language, encoding, or device type.

Some of the software used to generate or serve this page.
Warning Sharing too many details about a server or web application makes it easier for hackers to target a website. Avoid specific version numbers such as 1.7.0, especially when running software that is end-of-life and/or has known security bugs. Consider removing this header. At a miminum, remove any version number.

Some of the software used to generate or serve this page.

Some of the software used to generate or serve this page.

The Strict-Transport-Security header (HSTS) instructs browsers to only use HTTPS for future connections to this domain, enhancing security by preventing downgrade attacks and cookie hijacking.
max-age specifies the time, in seconds, that the browser should remember to use HTTPS only for this domain.
Notice For optimal security, consider increasing max-age to at least 31,536,000 seconds (1 year), especially if you're considering preloading.
includesubdomains instructs the browser that all subdomains are HTTPS-only as well.

The date and time at which the request was made. A browser uses it for age calculations rather than using its own internal date and time; e.g. when comparing against Max-Age or Expires.

missing Add a Content-Security-Policy header. The Content-Security-Policy header helps browsers prevent cross site scripting (XSS) and data injection attacks.

missing Add a Referrer-Policy header. When a visitor navigates from one page to another, browsers often pass along referrer information. The Referrer-Policy header controls how much referrer information a browser can share. This is important to configure when private information is embedded in the path or query string and passed onto an external destination.

missing Add a Permissions-Policy header. Restrict access to device features like the camera, microphone, location, accelerometer and much more.

missing Add a Cross-Origin-Embedder-Policy to specify how this page can be loaded by cross-origin resources.

missing Add a Cross-Origin-Opener-Policy header to opt-in into better browser isolation.

missing Add a Cross-Origin-Resource-Policy header to specify who can load this page.

missing Add a X-Frame-Options header. The X-Frame-Options header prevents this URL from being embedded in an iframe. This protects against clickjacking attacks. Alternatively, set a Content-Security-Policy header with a frame-ancestor directive.

missing Add a X-Permitted-Cross-Domain-Policies header to prevent Flash, Adobe Reader and other clients from sharing data across domains.