A marketplace idea often begins with listings and a checkout. Before building, define what the platform promises to buyers and sellers and which responsibilities remain with each participant.
Describe the complete transaction
Follow a purchase from discovery to fulfillment, cancellation and a problem report. Identify who confirms availability, who delivers the service and who handles a customer question.
Payment flows, provider eligibility, taxation and legal terms need the appropriate specialist review. A general software prototype should not be treated as approval of a financial operating model.
Choose a bounded first version
The first release may support inquiries or manually reviewed transactions while the business validates the operational process. Clearly label what the application does and what staff still handle.
Test participant onboarding, a listing change and an unresolved transaction. Decide what information each role can see and how access ends.
Bring the participant types, the customer journey and the business owner for policy decisions. That lets the development discussion focus on a workable service rather than a set of screens whose commercial responsibilities are still unclear.
Include the case where a seller cannot fulfill after a buyer expresses interest. Even an inquiry-only first version needs a clear status and support route for that ordinary exception.