> ## Documentation Index > Fetch the complete documentation index at: https://developers.appstle.com/llms.txt > Use this file to discover all available pages before exploring further. # Get currently logged-in customer ID > Returns the customer ID of the currently authenticated customer from their Shopify session. This endpoint is used by the customer portal UI to identify which customer is logged in. **Use Cases:** - Customer portal initialization - determine who's logged in - Fetch customer-specific data (subscriptions, orders, settings) - Validate customer session before displaying sensitive information - Personalize customer portal UI with customer name/email **How it works:** - Customer must be logged in to their Shopify customer account - Session is validated via Shopify App Proxy - Returns Shopify customer ID (numeric) **Important Notes:** - This endpoint only works when called from the shop domain (via Shopify App Proxy) - Customer must be logged in to Shopify - Returns null if customer is not authenticated - Do not use this for external API integrations - use External APIs with explicit customer ID instead **Authentication:** Requires active Shopify customer session (browser-based) ## OpenAPI ````yaml /subscription/storefront-api-swagger.json get /subscriptions/cp/api/logged-in-customer openapi: 3.0.1 info: description: >- Comprehensive API documentation for the customer-facing subscription portal. These APIs enable customers to manage their subscriptions, update billing information, modify delivery schedules, and access their account details through your storefront. **Important**: These APIs must be called from your shop's domain (e.g., https://www.myshop.com/apps/subscriptions/cp/api/**) and require customer authentication. Unauthenticated requests will return a 401 Unauthorized error. title: Storefront APIs version: 0.0.1 servers: - url: https://www.myshop.com/apps security: [] tags: - description: >- Core customer portal APIs for managing customer account settings, authentication, and portal configurations. name: Customer Portal - description: >- APIs for customers to view and manage their subscription contracts including status updates, frequency changes, and cancellations. name: Subscription Management - description: >- APIs for retrieving and updating subscription contract details — delivery schedules, line items, addresses, billing cycles. name: Subscription Contracts - description: >- APIs for retrieving available subscription plans and selling plan configurations exposed to customers. name: Subscription Plans - description: >- APIs for managing one-time add-on products that can be purchased alongside recurring subscription items. name: Subscription One-Time Products - description: >- APIs for retrieving aggregated subscription data and account-level subscription information for the signed-in customer. name: Subscription Data - description: >- APIs for managing customizable product boxes and bundles where customers can select multiple items. name: Build-a-Box & Bundles - description: >- APIs for managing payment methods, billing information, and processing subscription payments. name: Billing & Payments - description: >- APIs for retrieving product information, selling plans, variant data, and subscription-enabled products available to customers. name: Product Catalog - description: >- APIs for managing delivery schedules, shipping addresses, delivery methods, and tracking order status. name: Delivery & Shipping - description: >- APIs for handling subscription cancellations, retention activities, and customer feedback management. name: Customer Retention - description: >- APIs for integrating loyalty programs with subscriptions including points redemption and earning options. name: Loyalty Integration - description: >- APIs for accessing portal customization settings, translations, and theme configurations. name: Customization - description: >- APIs for retrieving promotional campaigns shown in the customer portal, tracking banner engagement, and redeeming campaign offers. name: Campaigns - description: >- APIs for local pickup and click-and-collect — listing pickup locations and resolving eligible pickup dates and time slots. name: Store Pickup paths: /subscriptions/cp/api/logged-in-customer: get: tags: - Subscription Contracts - Customer Portal summary: Get currently logged-in customer ID description: >- Returns the customer ID of the currently authenticated customer from their Shopify session. This endpoint is used by the customer portal UI to identify which customer is logged in. **Use Cases:** - Customer portal initialization - determine who's logged in - Fetch customer-specific data (subscriptions, orders, settings) - Validate customer session before displaying sensitive information - Personalize customer portal UI with customer name/email **How it works:** - Customer must be logged in to their Shopify customer account - Session is validated via Shopify App Proxy - Returns Shopify customer ID (numeric) **Important Notes:** - This endpoint only works when called from the shop domain (via Shopify App Proxy) - Customer must be logged in to Shopify - Returns null if customer is not authenticated - Do not use this for external API integrations - use External APIs with explicit customer ID instead **Authentication:** Requires active Shopify customer session (browser-based) operationId: updateSubscriptionContractDetails_1 responses: '200': content: application/json: examples: Logged in customer: description: Logged in customer value: 6548267876558 schema: example: 6548267876558 format: int64 type: integer description: Customer ID retrieved successfully '401': content: '*/*': schema: format: int64 type: integer description: Customer not logged in or invalid session ````