What is a DNT header?
"Do Not Track" - a now largely unsupported request that the client does not want its browsing tracked.
DNT was an early, largely voluntary attempt to let a visitor tell a website 'please don't track me across sites', but because honouring it was never legally mandated and major browsers have since dropped support for sending it, it's now mostly a historical footnote rather than something worth building privacy logic around today.
Common use case
A privacy-conscious analytics tool checks for DNT: 1 and, on sites that choose to honour it, skips setting tracking cookies or sending data to third-party trackers for that visitor.
Example
DNT: 1History
First implemented by Mozilla Firefox in 2010 as a voluntary proposal; drafted as a W3C specification that was ultimately abandoned in 2019 without ever reaching full standardisation.
Deprecated / legacy status
Never became a binding standard, and major browsers including Safari and Chrome have since removed the setting entirely, largely because so few sites ever honoured it that the header stopped providing any real privacy benefit.
Did you know?
Its short, strange life is often cited as a cautionary tale in privacy tech: a purely voluntary standard with no enforcement mechanism was, in the end, mostly ignored by the sites it was meant to constrain.