Checkout spans a cart, a server-priced order, a provider-owned payment flow, browser return pages, and asynchronous provider events. The browser is a user interface, not the authority for final amount or payment completion. This track uses a fictional equipment-store order with integer money values and a hosted payment page. It focuses on duplicate submissions, uncertain responses, verified callbacks, order fulfillment, and reversal states. Actual provider methods, currencies, and compliance scope require a chosen integration and current review.
Topics in this track
- Server-Priced Order Snapshots and Money Units — Build an immutable order total from trusted catalog data and currency-specific integer units.
- Hosted Checkout Sessions and Browser Returns — Bind a hosted payment attempt to a server order while treating the return page as a status view.
- Payment Webhook Reconciliation and Idempotent Fulfillment — Verify provider events and make order fulfillment safe under retries and out-of-order delivery.
- Refunds, Reversals, and Payment Ledger State — Track partial refunds and disputes as separate money movements with bounded, reconcilable state.
Prerequisite paths
Backend and API Systems; Signed Webhook Delivery and Replay Control.
Neighbor track
Passkeys and Account Assurance.
Practice path
Build Project: checkout reconciliation and check decisions in Web Development: passkey and checkout decisions quiz.