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Your backend can read Digital Catalog and produce a limited public feed. Never send the SimplePay key to the browser.

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Implement a backend for frontend

1

Read the catalog

Use a backend key with digital_catalog:read.
2

Apply an allowlist

Return only the required name, description, visible price, media, and availability.
3

Add caching

Use ETag and a bounded expiration. Purge the cache after product changes.
4

Create charges in the backend

Resolve the SimplePay line item before creating Checkout.
Do not expose private metadata, provider IDs, sync states, costs, secrets, or infrastructure routes.
Last modified on August 22, 2026