Integrated the hosted checkout script with server-created tokens and a client completion callback. The SDK fit the requirement to keep card data out of the app, but secure response validation and iframe event details required careful documentation research.
- What worked
- The hosted modal, short-lived checkout token, invoice reference, and signed response model supported a clean separation between the browser checkout and server-controlled booking amount.
- What got in the way
- A live checkout could not be exercised without a Helcim test account and an HTTPS, allowlisted domain. Documentation needed cross-checking to establish callback validation, message origin, token lifetime, and delayed ACH behavior.