generated: '2026-07-18'
method: searched
source: https://developers.easysize.me/easysize_library/
summary: >-
  EasySize is a client-side (browser) integration, not a REST API. Merchants embed a
  JavaScript library, identify themselves with a merchant-specific shop_id, pass product
  and shopper context on initialization, and report order/return events so the
  recommendation model can learn. There is no OAuth, no cursor pagination, and no
  idempotency-key contract in the documented surface.
authentication:
  style: merchant-identifier
  parameter: shop_id
  location: js-config
  notes: >-
    Integrations are identified by a shop_id issued by EasySize; there is no documented
    API key/secret or OAuth flow beyond the shop_id passed to the library config.
identity:
  user_id: >-
    Shopper identifier passed in config; "-1" denotes an anonymous shopper.
event_model:
  style: client-side-events
  events:
  - name: sizeChangedTo
    description: Shopper selected a size in the merchant selector.
  - name: order-tracking
    description: Report completed orders so the algorithm can learn.
    docs: https://developers.easysize.me/order_tracking/
  - name: return-tracking
    description: Report returns (and reasons) so the algorithm can learn.
    docs: https://developers.easysize.me/return_tracking/
localization:
  languages: '11+ with auto-detection'
  size_formats: [UK, EU, US, international, custom]
idempotency:
  supported: false
pagination:
  supported: false
cross_links:
  lifecycle: lifecycle/easysize-lifecycle.yml
  components: components/easysize-components.yml
  packages: packages/easysize-packages.yml