Price protection
A buyer page can display the offer, but checkout creation reads the backend product table. Browser-side amount changes do not override the saved USDC price.
Fixed Price Payment Link
Create payment links for products where the real price must be saved on the backend. Fixed price links are built for memberships, paid articles, downloads, courses, templates, packages, services, and public offers.
Membership periods
Fixed products can use validity days. For example, a 1 USDC membership can unlock access for 30 days, while 0 days can mean permanent access.
Downloads and paid articles
Use fixed product links for downloadable files, paid articles, private chapters, templates, course access, and single-purchase unlocks.
Records and deletion
Saved products keep payment records for reconciliation. If a product is deleted, the old link becomes inactive and quota is freed for another fixed product.
When to use fixed price payment links
Use a fixed price payment link when the product price should not depend on the front-end page. This is the correct model for public pricing, subscriptions, paid content, file downloads, course access, software licenses, and packaged services.
Use merchant code for flexible amounts such as custom invoices, tips, top-ups, balance adjustments, and backend-generated orders. Use fixed products when the merchant wants a saved product code with a known USDC price, validity period, optional settlement wallet, success URL, and button text.