| cart | esoworld.co.uk (first-party) | Stores your Shopify cart token so basket contents persist between page loads and across sessions. | Strictly necessary | 14 days (rolling) |
| session | esoworld.co.uk (first-party) | Server-side session identifier for the Hydrogen storefront. Required for the site to function. | Strictly necessary | Session |
| _shopify_y | Shopify (shopify.com) | Shopify visitor identifier used for fraud prevention, security and checkout state. | Strictly necessary | 1 year |
| _shopify_s | Shopify (shopify.com) | Shopify session identifier. Required for checkout to function. | Strictly necessary | Session |
| _shopify_d | Shopify (shopify.com) | Detects whether the visitor is on a mobile device; affects checkout layout. | Strictly necessary | Session |
| _secure_session_id | Shopify (shopify.com) | Hardened session identifier used during checkout to bind to the secure session. | Strictly necessary | Session |
| _cart_sig | Shopify (shopify.com) | HMAC signature protecting the cart token from tampering. | Strictly necessary | Session |
| _orig_referrer | Shopify (shopify.com) | Records the referrer at first visit so checkout displays correct context. | Strictly necessary | Session |
| _landing_page | Shopify (shopify.com) | Records the first page the visitor landed on so checkout can return them after authentication. | Strictly necessary | Session |
| country | esoworld.co.uk (first-party) | Stores the visitor’s selected country for currency and shipping. | Preferences | 1 year |
| eso_anonymous_id | esoworld.co.uk (first-party) | HttpOnly anonymous identifier used to stitch browse and purchase activity for the same visitor without exposing identity. Mirrors Klaviyo’s anonymous_id. | Functional | 2 years |
| eso_kx | esoworld.co.uk (first-party) | Stores the Klaviyo email-click identifier (_kx) when a subscriber arrives from an email link, so we can stitch the on-site activity onto their email profile. | Functional | 90 days |
| eso_sub_variant | esoworld.co.uk (first-party) | Records which Subscribe & Save layout variant was shown so the same visitor sees a consistent layout across pages. | Preferences | 180 days |
| eso_exchange_id | esoworld.co.uk (first-party) | Klaviyo exchange identifier (_kx) used to merge anonymous and email-known profiles when the visitor later identifies. | Functional | 1 year |
| _ga | Google Analytics (google.com) | Distinguishes unique users for Google Analytics 4 (GA4) reporting. | Analytics | 2 years |
| _ga_ZVNT72X93S | Google Analytics (google.com) | GA4 session-specific identifier for our property (G-ZVNT72X93S). | Analytics | 2 years |
| _gid | Google Analytics (google.com) | Distinguishes users for 24-hour Google Analytics reports. | Analytics | 24 hours |
| _clck | Microsoft Clarity (clarity.ms) | Persistent Clarity user identifier used for behavioural analytics (heatmaps, session replay). | Analytics | 1 year |
| _clsk | Microsoft Clarity (clarity.ms) | Clarity session identifier connecting page views in a single session. | Analytics | 1 day |
| _fbp | Meta (facebook.com) | Meta browser pixel identifier used to attribute conversions to Facebook / Instagram ads and build Custom Audiences. | Advertising | 90 days |
| _fbc | Meta (facebook.com) | Stores the Facebook click ID (fbclid) from ad clicks; used for conversion attribution. | Advertising | 90 days |
| _pin_unauth | Pinterest (pinterest.com) | Pinterest tag identifier for non-logged-in visitors; used for ad attribution and audience building. | Advertising | 1 year |
| _pinterest_ct_ua | Pinterest (pinterest.com) | Pinterest conversion-tracking identifier used for cross-device attribution. | Advertising | 1 year |
| _pinterest_sess | Pinterest (pinterest.com) | Pinterest session identifier for logged-in users; ad attribution. | Advertising | 1 year |
| _rdt_uuid | Reddit (reddit.com) | Reddit pixel identifier used to attribute conversions and build Reddit ad audiences. | Advertising | 90 days |
| _uetsid | Microsoft (bing.com) | Microsoft UET session identifier used for Bing Ads / Microsoft Advertising conversion tracking. | Advertising | 1 day |
| _uetvid | Microsoft (bing.com) | Microsoft UET persistent visitor identifier used for ad attribution. | Advertising | 13 months |
| _ttp | TikTok (tiktok.com) | TikTok pixel identifier used to attribute conversions to TikTok ad campaigns. | Advertising | 13 months |
| __ttp | TikTok (tiktok.com) | TikTok cross-site session identifier used for ad attribution. | Advertising | 13 months |
| __kla_id | Klaviyo (klaviyo.com) | Klaviyo profile cookie used for email-marketing attribution, abandoned-cart targeting and audience segmentation. | Advertising | 2 years |
| Local storage: eso_click_ids_v1 | esoworld.co.uk (first-party) | Stores ad-platform click identifiers (gclid, fbclid, msclkid, ttclid, epik, rdt_cid, wbraid) so conversions can be attributed back to the originating ad click. Mirrored into the Shopify cart so the order webhook can fire server-side CAPI events. | Advertising | 90 days |
| Local storage: eso_cart_attrs_fingerprint_v1 | esoworld.co.uk (first-party) | Caches the last set of click-attribution values attached to the cart so we do not re-attach on every page load. | Functional | Until cleared |
| Server-side webhook idempotency (Workers KV) | esoworld.co.uk (first-party) | Stores hashes of received Shopify webhook IDs for 7 days to prevent duplicate ad-platform conversion fires on webhook retries. Does not touch the browser. | Strictly necessary | 7 days |