Methods and systems for securely transferring and merging an electronic shopping cart curated by an affiliate online service for purchase on a retailer online service is disclosed. The retailer online service provides an anonymous token to the affiliate online service that allows the affiliate online service to curate an anonymous electronic shopping cart for a user that does not include any identifying information that links the user to a guest account of the retailer online service. When the user is redirected from the affiliate online service to the retailer online service, the anonymous token is validated. Upon validation of the anonymous token, the retailer online service obtains identifying information linking the user to the guest account of the retailer online service and obtain a pre-existing electronic shopping cart linked to the guest account. The retailer online service then merges the anonymous electronic shopping cart with the pre-existing electronic shopping cart.