Google Ads conversion-linker cookie. Stores ad-click information so conversions can be attributed outside Google's domain.

Google Ads click-through cookie set when a visitor lands on the site from a Google search ad. Used for attribution.

Google Ads / DoubleClick click-through cookie set when a visitor arrives from a Display Network ad.

Contains campaign-related information for the user. Linked to GA properties that have Google Ads auto-tagging enabled.

Used by Google DoubleClick to register and report on user actions after viewing or clicking an ad — for measuring effectiveness and serving targeted ads.

Set by doubleclick.net to determine if the user's browser supports cookies before serving ads.

Used by Google DoubleClick to identify a signed-in user across non-Google sites and remember whether they consented to ad personalisation.

Contains a unique ID Google uses to remember preferences (preferred language, ad personalisation) and to show targeted ads on Google services and across the web.

Used by Google to gather website statistics and track conversion rates. Set when Google domains are embedded (YouTube, reCAPTCHA, Maps).

Google account session cookie. On third-party sites (via YouTube, Maps, or reCAPTCHA embeds) it enables Google to identify a signed-in visitor across the web — a tracking-capable identifier that requires consent in EU/UK contexts.

Companion to SID, signed to prevent forgery. On third-party sites surfaced through Google embeds, it contributes to cross-site visitor identification and ad personalisation.

Secure first-party variant of the Google account session cookie. When surfaced on a third-party site through a Google embed, it enables Google to identify the visitor across the web for ad and product personalisation.

Third-party variant of the Google account session cookie. Enables Google to deliver personalised ads across non-Google sites.

Set by Meta Pixel (used by both Facebook and Instagram Ads) to identify browsers for ad delivery, conversion tracking, and remarketing.

Stores the last-click ID (fbclid) from a Facebook or Instagram ad that brought the visitor to the site. Used for ad attribution and conversion tracking.

Set by facebook.com when Meta widgets are embedded (Like button, comments, login). Used to deliver ads, measure ad performance, and personalise ad content across Facebook and Instagram.

TikTok Pixel cookie used to track conversions, optimise ad delivery, and build remarketing audiences.

TikTok web identifier used for analytics and ad performance measurement across the TikTok ad network.

Set by TikTok Pixel to confirm whether the visitor's browser will accept TikTok cookies before firing tracking events.

Persistent TikTok web visitor ID used for cross-session attribution and ad measurement.

Used by LinkedIn Insight Tag to make a probabilistic match of a visitor's identity outside the designated countries.

LinkedIn browser ID cookie used to identify devices accessing LinkedIn for analytics, ad measurement, and personalisation.

Secure browser ID used for LinkedIn account security. On third-party sites it surfaces through LinkedIn embeds and forms part of LinkedIn's cross-site identity layer used for ad measurement and remarketing.

Used by LinkedIn for ID-syncing of advertising campaigns across user devices.

Used by X (formerly Twitter) to integrate and share features for social media and to personalise content and ads across the X ad network.

Used by X to identify and track website visitors (including non-logged-in users) for embedded content, analytics, and ads.

Set by X to measure and improve the relevance of advertising shown on the X platform and via the X Audience Platform on third-party sites.

Used by Pinterest for tracking purposes and to enable users to share content via the Pinterest social network.

Pinterest uses this cookie to group actions for users who cannot be identified by Pinterest (non-logged-in visitors).

Used by the Pinterest conversion tag to attribute on-site events to Pinterest ad campaigns.

Snapchat Pixel browser identifier used to track conversions and measure the effectiveness of Snapchat ads.

Snapchat authentication / ad-attribution cookie used to associate visitors with Snapchat ad clicks.

Reddit Pixel visitor identifier. Used to measure conversions, build remarketing audiences, and attribute on-site events to Reddit ad clicks.

Criteo's primary retargeting cookie. Stores an encoded bundle that links the visitor to Criteo's ad-bidding profile for personalised display ads.

Used by Criteo to determine the highest-level domain on which it can set cookies. Set briefly during the test, then expires.

Stores a Criteo identifier copied from a related domain to maintain retargeting state across multiple TLDs.

Criteo session identifier used to deduplicate ad impressions and conversion events within a single browsing session.

Microsoft Bing Ads UET (Universal Event Tracking) session cookie. Used for conversion measurement and audience building for Bing/Microsoft Ads campaigns.

Microsoft Bing Ads UET visitor cookie. Persistent ID used for cross-session attribution and remarketing for Microsoft Advertising.

Microsoft user identifier set on bing.com and microsoft.com. Used for user identification, ad personalisation, and analytics across Microsoft properties — including Bing Ads on third-party sites.

Set by bing.com to register a unique ID that identifies a returning user's device for Bing Ads remarketing.

Used by Microsoft Clarity / Bing to validate analytics data and prevent fraudulent UET event submissions.

Used by Microsoft to indicate whether to refresh the MUID cookie. Supports Bing Ads attribution and audience syncing.

Mailchimp marketing cookie used to identify the visitor and link form submissions to a Mailchimp audience.

Klaviyo identifier cookie. Tracks the visitor across sessions for email campaign attribution and audience syncing.