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 Accept-CH header specifies HTTP Client Hints that the server requests from the client (typically a browser) to optimize content delivery.

• sec-ch-ua-bitness: Requests the bit architecture of the client's operating system, such as 32-bit or 64-bit.
• sec-ch-ua-arch: Requests the client's device CPU architecture, such as ARM or x86.
• sec-ch-ua-full-version: Requests the complete version number of the client's browser.
• sec-ch-ua-mobile: Requests a boolean hint indicating if the client's device is mobile.
• sec-ch-ua-model: Requests the model of the client's device.
• sec-ch-ua-platform-version: Requests the version of the operating system the client is running.
• sec-ch-ua-full-version-list: Requests a detailed list of version numbers for the client's browser and its significant components.
• sec-ch-ua-platform: Requests the operating system platform of the client's device, such as Windows or MacOS.
• sec-ch-ua: Requests a condensed version of the user agent string.
• ua-bitness: Requests the bit architecture of the client's operating system, such as 32-bit or 64-bit.
• ua-arch: Requests the client's device CPU architecture, such as ARM or x86.
• ua-full-version: Requests the complete version number of the client's browser.
• ua-mobile: Requests a boolean hint indicating if the client's device is mobile.
• ua-model: Requests the model of the client's device.
• ua-platform-version: Requests the version of the operating system the client is running.
• ua-platform: Requests the operating system platform of the client's device, such as Windows or MacOS.
• ua: Requests a condensed version of the user agent string.

Specifies if this page can embed cross-origin resources. Allowing an attacker to embed a page and load its context into their memory space could result in data leaks. This header shifts the default behavior to an explicit opt-in model; the actual policy is specified in either a seperate Cross-Origin-Resource-Policy header or a CORS check.
require-corp specifies that this page can only embedded resources from the same origin, or resources explicitly marked as loadable from another origin.

A Cross-Origin Opener Policy (COOP) header specifies how this page's browsing context can be shared when opened in a 'browser tab', 'popup', 'iframe', etc. The policy can force the creation of a new top-level browsing context to make sure the browser context is protected or isolated.
same-origin specifies that the page can only share the browsing context with other pages from the same origin.

The Cross-Origin-Resource-Policy header is part of the Fetch metadata request headers. It controls how resources can be shared across origins, enhancing security by preventing unauthorized access to resources.
same-origin means the resource can only be loaded by documents from the same origin.

A security header that enables or disables the "Origin-Agent-Cluster" isolation for a document. When set to "?1", it indicates that the document should be placed in an origin-keyed agent cluster, which can enhance security isolation.

Instructs a browser to selectively allow or deny certain browser APIs and features. It helps improve security.

When a visitor navigates from one page to another page, browsers often pass along referrer information. The Referrer-Policy header controls how much referrer information a browser can share. This is important because private information can be embedded in the path or query string.
same-origin means that the protocol, host, port, path and query string are shared for same-site requests. For cross-site requests, nothing is shared.

X-Frame-Options prevents this URL from being embedded in an iframe. This protects against clickjacking attacks.
sameorigin means that this page can be displayed in a iframe, but only on the currrent origin. It can't be displayed on another domain. Consider setting this to deny for added security.

The cf-mitigated header indicates that Cloudflare detected and mitigated a potential security threat. The value specifies which Cloudflare security feature was triggered, such as WAF (Web Application Firewall) rules or DDoS protection measures.

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.
Notice pre-check is a legacy directive introduced by Internet Explorer 5 and is no longer supported. No other browser supports it. Including pre-check is unnecessary, wastes bandwidth and processing power.
Notice post-check is a legacy directive introduced by Internet Explorer 5 and is no longer supported. No other browser supports it. Including post-check is unnecessary, wastes bandwidth and processing power.

This Expires date is in the past: the page is considered stale and will be removed from all caches.
Notice Because there is a Cache-Control header with a max-age and/or s-maxage directive, the Expires header will be ignored. Consider removing Expires to save bandwidth and processing power.

This header is part of the Reporting API specification. They are used to configure the reporting of network errors and other issues to a specified endpoint.
The Report-To header specifies where reports should be sent.
group defines the reporting group. Groups allow reports to be grouped logically; e.g. there could be a group for network errors and a second group for browser feature deprecation reports.
max_age defines the number of seconds the browser should remember these settings. Prevents the browser from having to parse the JSON on each request.
endpoints defines one or more URLs where the reports need to be send to. Multiple URLs can be specified for failover and load-balancing. Endpoints can be assigned a weight to distribute load, with each endpoint receiving a specified fraction of the reporting traffic. Endpoints can also be assigned a priority to set up fallback collectors.

This header is part of the Reporting API specification. They are used to configure the reporting of network errors and other issues to a specified endpoint.
The NEL (Network Error Logging) header configures the reporting of network errors.
report_to defines the reporting group that reports for this NEL policy will be sent to. The reporting group details are specified in the Report-To header.
max_age defines the number of seconds the browser should remember these settings. Prevents the browser from having to parse the JSON on each request.
success_fraction defines the sampling rate that should be applied to reports about successful network requests. Its value must be a number between 0.0 and 1.0: 0 means no successful requests should be reported, and 1 means that every successful request should be reported.

The cf-ray header provides a unique identifier for each request through Cloudflare. It's useful for troubleshooting and tracking requests in Cloudflare logs.

The alt-svc header advertises alternative services for accessing the same resource, enabling protocol negotiation and potential performance improvements.
h3 indicates that HTTP/3 is supported. Variants like h3-29 refer to specific drafts of the HTTP/3 protocol.
ma=86400 specifies that the alternative service information is fresh for 86400 seconds.

Communicates one or more metrics for a given request-response cycle. Can includes metrics for CPU time, database read/writes, file system access, etc.

missing Add a Strict-Transport-Security header. The Strict-Transport-Security header or HSTS header is used to instruct browsers to only use HTTPS, instead of using HTTP. It helps enforce secure communication.

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