Service Communication and API Design Questions
Design and specify APIs and interservice communication patterns for systems that must scale. Topics include REST design and best practices, API versioning and deprecation strategies, backward compatibility and API evolution, contract design between services, choosing protocols such as gRPC versus HTTP for internal or external communication, security and authentication patterns at the API level, performance and scalability considerations, observability and monitoring of service interactions, and strategies for evolving interfaces without breaking consumers.
HardSystem Design
50 practiced
You operate a long-lived Server-Sent Events (SSE) streaming API used by thousands of clients. You must evolve the event schema without disconnecting clients. Design a schema-versioning strategy, server capability negotiation, and migration path that allows older clients to continue receiving usable events while enabling new fields for updated clients.
EasyTechnical
40 practiced
Explain webhook fundamentals and typical design concerns such as retries, idempotency, authentication/signature verification, delivery guarantees, and how to design a polite retry/backoff strategy. Provide a sample webhook payload shape and explain how a receiver should validate and acknowledge it.
MediumSystem Design
41 practiced
Design a globally-distributed rate limiting system that supports per-user, per-API-key, and per-endpoint quotas, enforcing 100 requests/min per user with burst capacity. Discuss trade-offs between a centralized Redis store, local in-memory token buckets with eventual consistency, and a dedicated rate-limiter service, and sketch the data structures you'd use.
HardTechnical
81 practiced
Implement a thread-safe Java helper that wraps HTTP calls and provides exponential backoff with full jitter (max backoff), a circuit breaker with closed/open/half-open states and sliding window failure counts, and optional request-batching for POST operations. Provide the class skeleton, key methods, and pseudocode for state transitions and backoff calculation.
MediumSystem Design
45 practiced
Design an observability strategy for interservice API calls across hundreds of microservices: include trace propagation (W3C tracecontext), span granularity, metrics to track per-endpoint latency and error rates, sampling strategy, alerting rules for SLOs, and dashboards you'd build for on-call teams.
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