Dries Buytaert

Explanation

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.

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

The size of the message body, in bytes.

A cookie that was sent from the server to the browser.
expires= sets the maximum lifetime of the cookie using a specific date.
path= indicates the path that must exist in the requested URL for the browser to send the cookie.

A cookie that was sent from the server to the browser.
expires= sets the maximum lifetime of the cookie using a specific date.
path= indicates the path that must exist in the requested URL for the browser to send the cookie.
Warning samesite=none instructs the browser to send the cookie to all cross-site requests, such as on requests to load images or frames from other sites. This enables third-party sites to log cookie data. This could lead to data leaks and cross-site request forgery attacks. To improve security, set to samesite=strict or samesite=lax.
secure instructs the browser to only send the cookie back when HTTPS requests are used, making it more resistant to man-in-the-middle attacks.

private means the response can only be stored by the browser's cache, but not by CDNs, proxies, or any other shared caches.
no-cache means the response can be stored by any cache, but the stored response must be validated with the origin server before each reuse. If the origin confirms that the response hasn't changed, downloading of the full response body can be skipped.
Warning no-cache will cause a revalidation request to the origin server for every use of the cached response. Consider using public with appropriate max-age to improve caching efficiency.
Warning no-store means the response may not be stored in any cache, including the browser's cache.
max-age=0 with must-revalidate means caching is disabled and all requests must be validated with the origin server.
Notice It does not make sense to set must-revalidate with no-store; when nothing is cached, there is nothing to revalidate.
Notice It does not make sense to set must-revalidate with no-cache; must-revalidate is implied.
Notice no-store is set, so it does not make sense to set no-cache as well.
Notice no-store is set, so it does not make sense to set private as well.

Warning The page can't be cached by any shared caches such as Varnish or a CDN. If the page is something everybody can access, this behavior is not desired.
Notice Pragma is a HTTP/1.0 header. This request uses HTTP/1.1. In HTTP/1.1, Pragma is deprecated and superseded by the Cache-Control header. Remove Pragma to save bandwidth and processing power.

The page was served from a cache.

The page was served from a cache.

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 8.12.2, 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.

Allows web developers to debug content security policies. Violations are reported to the specified report-uri, but not enforced.

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.

Indicates which HTTP methods can be used.

Indicates which HTTP headers can be used.

Specifies which headers can be exposed to the client in a CORS (Cross-Origin Resource Sharing) context.

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.
includesubdomains instructs the browser that all subdomains are HTTPS-only as well.

The X-Content-Type-Options header, when set to nosniff, prevents MIME type sniffing. This enhances security by ensuring browsers respect the declared Content-Type of the response, mitigating MIME confusion attacks.
The value nosniff is correctly set, providing protection against MIME type sniffing attacks.

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.