HTTP Headers Analyzer
5 / 10
Header
Value
Explanation
expires
wed, 27 sep 2023 05:42:10 gmt
The date and time after which the page should be considered stale and all caches should be refreshed.
Notice Because there is a
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.date
wed, 27 sep 2023 05:42:10 gmt
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 compairing against
Max-Age
or Expires
.cache-control
private, max-age=0
private
means the page can only be stored by the browser, but not by CDNs, Varnish or any other shared caches.max-age
specifies the maximum amount of seconds a page is considered valid. The higher max-age
, the longer a page can be cached.Warning Because
max-age
is set to 0 seconds, nothing will ever be cached in shared caches or browsers. Caching is effectively disabled!last-modified
wed, 13 sep 2023 00:55:23 gmt
The date and time at which the origin server believes the page was last modified.
Notice Because there is an
Notice Because there is an
Etag
header, Last-Modified
is likely to be ignored. The ETag
hash is more accurate than the date/time in Last-Modified
. Consider removing Last-Modified
to save bandwidth and processing power.etag
w/"fda36be94f96182422eaf6284a34fb12e5821f77069b2e425ab68cb9f3d5d288"
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 hasHeaderWithName, the web server sends back a 304 Not Modified
status and no body. This particular Etag
value starts with w/
which means that it is a weak identifier; while unlikely, multiple pages might have the same identifier. Weak identifiers are used because strong identifiers can be difficult and costly to generate.x-content-type-options
nosniff
Instructs the browser not to change the MIME type of the request. Browsers sometimes sniff or inspect the document to determine if the specified MIME type is correct. A browser changing the MIME type of a document can introduce security vulnerabilities. These vulnerabilities can occur when a website allows users to upload content and the user disguises a particular file type as something else. For example, a JavaScript file is uploaded as a JPEG file. When the browser changes the MIME type from
image/jpeg
to test/javascript
, it gives attackers an opportunity to perform a cross-site scripting attack.x-xss-protection
1; mode=block
1; mode=block
enables the browser's cross-site scripting (XSS) filtering. Browsers that support X-Xss-Protection
will stop rendering the page when an attack is detected.Notice It is recommended to use
Content-Security-Policy
instead of X-XSS-Protection
. Some browsers like Firefox refuse to support X-XSS-Protection
. Content-Security-Policy
is more advanced, a W3C recommendation, and supported by all modern browsers.content-length
0
The size of the message body, in bytes.
server
gse
Some of the software used to generate or serve this page.
alt-svc
h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
Used to promote alternative services through which the same resource can be retrieved.
h3
stands for HTTP/3. The number after the dash indicates the draft; e.g. h3-27
would be draft 27 of the HTTP/3 protocol.ma
is the number of seconds the alternative service is considered fresh.strict-transport-security
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.content-security-policy
missing Add a
Content-Security-Policy
header. The Content-Security-Policy
header helps browsers prevent cross site scripting (XSS) and data injection attacks.referrer-policy
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.permissions-policy
missing Add a
Permissions-Policy
header. Restrict access to device features like the camera, microphone, location, accelerometer and much more.cross-origin-embedder-policy
missing Add a
Cross-Origin-Embedder-Policy
to specify how this page can be loaded by cross-origin resources.cross-origin-opener-policy
missing Add a
Cross-Origin-Opener-Policy
header to opt-in into better browser isolation.cross-origin-resource-policy
missing Add a
Cross-Origin-Resource-Policy
header to specify who can load this page.x-frame-options
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.x-permitted-cross-domain-policies
missing Add a
X-Permitted-Cross-Domain-Policies
header to prevent Flash, Adobe Reader and other clients from sharing data across domains.Questions or feedback? Email dries@buytaert.net.