Prep Room
HomeInterview SimulatorContestsYour JobsSalary negotiationUpskillResourcesConcept guidesResume
Concept guidesMaking a write safe to retryMid

There is more of this guide.

Practice

8 questions
  • API designDesign a payment-initiation endpoint. How do you make it safe to retry without charging twice?
  • API designDesign a CREATE endpoint that callers may retry on network errors. Walk me through the contract you'd offer.
  • API designShould DELETE be idempotent in your API? Walk me through both directions and what you'd actually ship.
  • API designYou're designing an endpoint that lets users update their email address. What happens if the same request is sent twice by accident? How do you prevent unintended side effects?
  • API designA user clicks 'submit order' twice because the page was slow. How would you design the order creation endpoint to handle this gracefully?
  • API designYour endpoint sends an SMS through a third-party provider that offers no idempotency support, and your callers retry on timeouts. How do you keep one logical request from sending three texts?
All questions
HomeYour JobsResumeResources
© 2026 Prep Room·From California·AI can make mistakes.
LegalAboutInsightsContactYour privacy choices