Product design question

Design a credit card system.

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Tests product and systems design for a regulated financial product, balancing user needs, fraud risk, and issuer constraints.

Clarify scope: card issuance for businesses versus a consumer credit card, and confirm with the interviewer.
Identify the user: a business wanting to issue employee expense cards, given the company's actual product context.
Define requirements: instant virtual card issuance, programmable spend controls, real-time authorization decisions.
Design the flow: API-driven card creation, spend rules, webhook-based transaction notifications.
Prioritize fraud and risk controls, like velocity limits, as core requirements, not an add-on.
Define success as approval rate for legitimate spend, fraud loss rate, and time-to-issue a new card.

Grounds the design in the company's actual product space, programmable card issuing, not a generic consumer card.
Treats fraud and risk controls as core, matching how real card systems are built under regulatory scrutiny.
Picks metrics that balance approval rate against fraud loss, the real trade-off in authorization systems.

Designing a generic consumer credit card without addressing issuance mechanics or fraud controls.
Ignoring the regulatory and compliance dimension of card issuing.

How would you set spend controls without being too restrictive for legitimate use?
How would you handle disputed transactions?
What would you measure to detect a rise in fraud early?