Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The Tk response header indicates the tracking status that applied to the corresponding request.

Header type Response header
Forbidden header name no


Tk: !  (under construction)
Tk: ?  (dynamic)
Tk: G  (gateway or multiple parties)
Tk: N  (not tracking)
Tk: T  (tracking)
Tk: C  (tracking with consent)
Tk: P  (potential consent)
Tk: D  (disregarding DNT)
Tk: U  (updated)



Under construction. The origin server is currently testing its communication of tracking status.


Dynamic. The origin server needs more information to determine tracking status.


Gateway or multiple parties. The server is acting as a gateway to an exchange involving multiple parties.


Not tracking.




Tracking with consent. The origin server believes it has received prior consent for tracking this user, user agent, or device.


Potential consent. The origin server does not know, in real-time, whether it has received prior consent for tracking this user, user agent, or device, but promises not to use or share any DNT:1 data until such consent has been determined, and further promises to delete or permanently de-identify within 48 hours any DNT:1 data received for which such consent has not been received.


Disregarding DNT. The origin server is unable or unwilling to respect a tracking preference received from the requesting user agent.


Updated. The request resulted in a potential change to the tracking status applicable to this user, user agent, or device.


A Tk header for a resource that claims not to be tracking would look like:

Tk: N


No specification found

No specification data found for http.headers.Tk.
Check for problems with this page or contribute a missing spec_url to mdn/browser-compat-data. Also make sure the specification is included in w3c/browser-specs.

Browser compatibility

BCD tables only load in the browser

See also