- React/Next.js: server vs. client components, data fetching, hydration, routing, performance
- Advanced concepts (less common): streaming responses, structured logging, feature flags, SSR caching, edge runtimes
Example questions or scenarios:
- “Implement a paginated search endpoint in NestJS with validation, error handling, and tests.”
- “Refactor a React component to improve performance and accessibility while preserving behavior.”
- “Design a typed SDK function that wraps a provider call and enforces structured output.”
System Design and Architecture
You’ll be evaluated on your ability to design extensible, observable, secure systems that integrate web frontends, APIs, event streams, and data stores. Interviewers look for crisp diagrams, explicit contracts, and reasoning about throughput, latency, and guardrails.
Be ready to go over:
- API design: versioning, pagination, idempotency, contracts (REST/GraphQL), authN/Z
- Event-driven patterns: Kafka/Redis streams, retries/DLQs, idempotency keys, eventual consistency
- Data modeling: Postgres schema design, indexing, migrations, partitioning, caching layers
- Advanced concepts (less common): multi-tenant isolation, backpressure strategies, CDC, real-time comms (WebSocket/WebRTC/Twilio)
Example questions or scenarios:
- “Design a provider-matching service that ingests events, ranks results, and serves a real-time UI.”
- “Propose an architecture for long-running tasks (Agent-as-a-Service) with retries, observability, and cancellation.”
- “Evolve a monolith endpoint into a service with clear SLAs, rate limiting, and rollbacks.”
AI/LLM Platform Fundamentals
Even if you’re not on the Agentic Platform team, you should understand what it takes to build safe, reliable AI features. Interviewers assess how you abstract providers, manage prompts, evaluate non-deterministic outputs, and protect users and data.
Be ready to go over:
- Provider abstraction: adapters for OpenAI/Anthropic/Google, token accounting, streaming
- Safety/guardrails: PII detection/redaction, content filters, schema-constrained outputs, audit logging
- Evaluation: datasets, metrics (exact match, LLM-as-judge), CI/CD gates, regression detection
- Advanced concepts (less common): tool invocation patterns, context packing, prompt versioning, offline vs. online evaluation
Example questions or scenarios:
- “Design a prompt-lifecycle system with versioning, approvals, and rollback integrated with GitHub.”
- “Build a structured-output layer that validates and repairs LLM responses against a TypeScript schema.”
- “How do you contain provider churn so downstream apps don’t break with each SDK update?”
Data, Observability, and Reliability
You will be asked how you know a system is healthy and improving. Expect questions about metrics selection, tracing, log quality, and alerting that reflects user impact. Reliability and performance are responsibilities—own them.
Be ready to go over:
- Metrics/SLIs/SLOs: latency, error budgets, Web Vitals, queue depth, token spend
- Observability: structured logs, distributed tracing, correlation IDs, redaction
- Perf/Resilience: caching strategies, circuit breakers, backoff, bulkheads
- Advanced concepts (less common): privacy-first telemetry, sampling strategies, chaos testing
Example questions or scenarios:
- “Instrument a feature from scratch: what do you log, trace, and alert on—and why?”
- “Reduce a P95 latency regression without increasing error rates—what levers do you pull?”
- “Design a redaction layer that guarantees no PII leaves the boundary of observability tools.”
Product Thinking and Cross-Functional Collaboration
Engineering decisions must be tied to customer value and business outcomes. Interviewers will look for how you size impact, create alignment, and iterate with stakeholders across Product, Marketing/SEO, Data, and Design.
Be ready to go over:
- Prioritization: value vs. effort framing, milestone slicing, risk management
- Experimentation: A/B testing, metrics definition, guardrails, interpretation pitfalls
- Documentation & influence: ADRs, design docs, RFCs, cross-team demos
- Advanced concepts (less common): SEO-aware architecture, content modeling, schema.org usage
Example questions or scenarios:
- “You discover a dependency risk mid-sprint—walk us through stakeholder alignment and path to green.”
- “Propose an experiment to improve conversion on the care-search flow. What metrics and guardrails?”
- “Translate a vague business goal into technical milestones with clear success criteria.”