Product Comparison

Also known as: compare_items, Compare Products, Product Compare, Add to Compare, Comparison Tool Use

EngagementeventE-commerce: Product Discovery & Merchandising (Search/Filters/PDP)E-commerce

Custom compare_items event, fired when a shopper adds a product to, removes it from, or opens the side-by-side comparison tool. Carries the compared items[] and compare_count so tray use can be tied to purchase.

Event Serialization

always

Business Use Case

["1️⃣ Merchandising: compare views high but add-to-cart low in a category → fixes spec gaps on the PDPs being compared.","2️⃣ Product: few shoppers reach the view step after adding two items → tests a sticky compare tray with a clear CTA.","3️⃣ E-commerce Marketing: one pair of products is compared often → builds a comparison guide for them.","4️⃣ Merchandising: a product is removed from trays more than kept → reviews its price and spec position against rivals."]

Business Criticality

Medium

Journey / Navigation Area

Discovery

Owning Function

Merchandising

Calculation Notes

["1️⃣ Fires when the compare tray changes (add, remove) or the comparison view renders (view); never on hover or a failed tick.","2️⃣ Serialization always: every add, remove and view is a hit. Count unique compared products per session by item_id at reporting time.","3️⃣ Required: compare_action, items, compare_count. Optional: item_list_id, item_list_name, page_type, currency, value.","4️⃣ add and remove send only the item changed; view sends every product in the tray. compare_count is the tray size after the change.","5️⃣ Tray at its configured maximum or duplicate add: no hit, the tray did not change. Reloading the comparison page fires view again.","6️⃣ No PII: items carry catalog fields only. Runs under the analytics consent category; drop the hit when analytics consent is denied.","7️⃣ Common mistake: a custom name like compare_click per button. Keep one event, compare_items, and split behaviour with compare_action."]

Platform Events

Platform	Event
Google Analytics 4	compare_items
Adobe	compareItems

Data Mappings

W3 Data Layer

{
  "digitalData": {
    "page": {
      "category": {
        "pageType": "pdp"
      }
    },
    "product": [
      {
        "productInfo": {
          "productID": "SKU-1",
          "productName": "item",
          "manufacturer": "brand"
        },
        "category": {
          "primaryCategory": "category"
        },
        "attributes": {
          "item_variant": "variant",
          "price": 100
        }
      }
    ],
    "event": [
      {
        "eventInfo": {
          "eventName": "compare_items",
          "eventAction": "add"
        },
        "attributes": {
          "compare_action": "add",
          "compare_count": 2,
          "item_list_id": "list-1",
          "item_list_name": "list",
          "currency": "USD",
          "value": 100
        }
      }
    ]
  }
}

GA4 Data Layer

{
  "event": "compare_items",
  "compare_action": "add",
  "compare_count": 2,
  "item_list_id": "list-1",
  "item_list_name": "list",
  "page_type": "pdp",
  "ecommerce": {
    "currency": "USD",
    "value": 100,
    "items": [
      {
        "item_id": "SKU-1",
        "item_name": "item",
        "item_brand": "brand",
        "item_category": "category",
        "item_variant": "variant",
        "price": 100
      }
    ]
  }
}

Adobe Client Data Layer

{
  "event": "compareItems",
  "eventInfo": {
    "compare_action": "add",
    "compare_count": 2,
    "item_list_id": "list-1",
    "item_list_name": "list",
    "page_type": "pdp",
    "currency": "USD",
    "value": 100
  },
  "productListItems": [
    {
      "SKU": "SKU-1",
      "name": "item",
      "priceTotal": 100,
      "currencyCode": "USD",
      "productCategories": [
        {
          "categoryName": "category"
        }
      ],
      "selectedOptions": [
        {
          "attribute": "variant",
          "value": "variant"
        }
      ],
      "_<tenantId>": {
        "brand": "brand"
      }
    }
  ]
}

XDM Mapping

{
  "eventType": "compare_items",
  "identityMap": {
    "ECID": [
      {
        "id": "ecid-1",
        "authenticatedState": "ambiguous",
        "primary": true
      }
    ]
  },
  "productListItems": [
    {
      "SKU": "SKU-1",
      "name": "item",
      "priceTotal": 100,
      "currencyCode": "USD",
      "productCategories": [
        {
          "categoryName": "category"
        }
      ],
      "selectedOptions": [
        {
          "attribute": "variant",
          "value": "variant"
        }
      ],
      "_<tenantId>": {
        "brand": "brand"
      }
    }
  ],
  "_<tenantId>": {
    "compareAction": "add",
    "compareCount": 2,
    "itemListId": "list-1",
    "itemListName": "list",
    "pageType": "pdp",
    "value": 100
  }
}

Parameters

{
  "items": "array - products affected: item_id, item_name, item_brand, item_category, item_variant, price; all tray items on view",
  "value": "number - optional; sum of price across items in the hit",
  "currency": "string - optional; ISO 4217 code for item prices, required if value is sent",
  "page_type": "string - optional; page where the action happened: plp, pdp, search or compare",
  "item_list_id": "string - optional; id of the list the product was added from, e.g. category_shoes",
  "compare_count": "integer - number of products in the comparison tray after the action",
  "compare_action": "string - add, remove or view; which compare-tray action fired the event",
  "item_list_name": "string - optional; name of the list the product was added from, e.g. Running Shoes"
}

Source Data

Digital Analytics (GA4)

Dependencies

Prerequisite: List the dependencies required for this Event

Report Attributes

compare_action Product Name Item Category Page Type Item List Name Device Category

Segment Eligibility

true

Governance

Data SensitivityInternal

Dimensions

Related Dimensions

product-name item-category page-type device-category price-band

Derived Entities

Derived Metrics

products-compared

Governance & Metadata

Created bydevyendarm

Created on10/11/2026

Last modified bydevyendarm

Last modified on10/11/2026

StatusPUBLISHED

GitHub

View related Pull Requestcatalog/events/product-comparison.yml