API Design and Integration Questions

Design and evaluate application programming interfaces for external and internal consumption. Topics include resource and schema modeling for RESTful APIs, GraphQL schema and resolver design for diverse clients, and when to choose gRPC style remote procedure calls for high performance internal services. Candidates should address consistent error responses including problem details, pagination and filtering strategies, versioning and deprecation plans, idempotency keys and safe retry semantics, rate limiting headers and status codes, authentication and authorization patterns, contract testing, monitoring and observability, and how to balance backward compatibility with iteration velocity.

MediumTechnical

23 practiced

Design a pagination API for a resource where clients need filtering, multi-column sorting, and consistent results even under concurrent writes. Provide example request query parameters and describe server-side considerations (indexes, stable sort keys, whether to return total counts). Discuss trade-offs between UX and performance.

EasyTechnical

26 practiced

Define idempotency in the context of HTTP APIs. Explain why it matters for operations like payments and order creation, how you would implement idempotency keys for POST endpoints, what server-side behavior you expect when duplicates arrive, and how to communicate idempotency semantics to API consumers.

HardSystem Design

28 practiced

Architect a hybrid API platform that supports REST, GraphQL, and gRPC, with features including an API gateway, schema/contract registry, developer portal with SDK generation, centralized monitoring, and per-tenant quotas. Define high-level components, control plane vs data plane responsibilities, and how you would enforce cross-cutting policies (auth, rate limits, versioning) at scale (millions of requests per day).

MediumTechnical

27 practiced

Design a reliable webhook system for third-party integrators. Include subscription handshake, payload signing/verification, retry and backoff strategy, idempotency and deduplication on receiver failures, monitoring/alerting for failing endpoints, and how to communicate subscription health to the integrator.

EasyTechnical

26 practiced

Describe how you would design consistent error responses for a public API using the Problem Details for HTTP APIs format (RFC 7807). Which fields are required versus optional, what additional fields would you include for integrator support (e.g., machine-readable error codes, correlation IDs, retryability flag), and how would this help SDKs and partner integrations?

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