InterviewsVector
IntermediateSeniorAPIs, Events & Integration45 minutesPro answer

SDV-025

Evolve a public API for five years without freezing the product

Balance compatibility, semantic versioning, deprecation, client capability, and operational evidence for an API customers cannot upgrade on command.

Api DesignSchema EvolutionChange ManagementObservability

Interview prompt

Problem context

An enterprise API has thousands of clients, several SDKs, and integrations that may remain unchanged for years. Product needs new semantics and stricter validation, while support cannot sustain every historical behavior forever. Design contracts, rollout, and deprecation.

Skills being evaluated

API evolutioncompatibility reasoningdeprecation policyclient observability

The full reasoning guide is part of Pro

The scenario and evaluation focus above remain public. Pro unlocks the structured answer, trade-off analysis, follow-up probes, common weak answers, rubric, related reasoning, and any architecture diagram.

Sign in to continue

What the full guide covers

Clarify the decision
Establish scale assumptions
Functional and non-functional requirements
High-level architecture
Data model and flow
Consistency and transaction boundaries
Failure modes and recovery
Security and privacy
Observability and SLOs
Capacity and cost
Alternatives and trade-offs
Evolution and migration
What Staff and Principal candidates should emphasize

Related architecture decisions

Staff · 55 min

Evolve event schemas across forty teams without central paralysis

Combine compatibility rules, ownership, consumer evidence, contract tests, and exception governance for a large event ecosystem.

Principal · 60 min

Migrate a wire protocol across a fleet without a flag day

Negotiate capabilities, preserve forward and backward compatibility, canary mixed versions, and retire old framing with evidence.

Principal · 60 min

Sunset a platform when the last users are the most powerful stakeholders

Retire long-tail capability through usage evidence, migration economics, exceptions, contractual leverage, and executive accountability.

Staff · 50 min

Deliver webhooks with semantics customers can actually prove

Design at-least-once delivery, ordering domains, signatures, replay, customer diagnostics, and provider-side backpressure without promising exactly once.