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


Specification Status Comment
Tracking Preference Expression (DNT)
The definition of 'Tk header field' in that specification.
Obsolete Initial definition.

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
TkChrome ? Edge ? Firefox ? IE ? Opera ? Safari ? WebView Android ? Chrome Android ? Firefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android ?


Compatibility unknown
Compatibility unknown

See also