_gcl_au is set by Google (via Google Ads / gtag.js) to help attribute ad clicks to on-site conversions.
Who sets it
Google — delivered via Google Ads / gtag.js.
What it does
Stores a conversion linker token used to attribute ad clicks to on-site conversions such as purchases and sign-ups.
Duration
90 days.
Consent
Used for marketing/advertising purposes — requires GDPR marketing consent where applicable.
How to remove
Remove via your browser's cookie controls or privacy settings; see your browser's cookie inspector for details.
Short-lived conversion linker cookie from Google — controlled via browser settings or consent tools.