Start by clarifying requirements (e.g., expected scale, regional availability, compliance needs) and then walk through the design in a structured, top-down manner: API, data model, validation, security, verification, anti-abuse, integrations, storage, and scaling. Emphasize trade-offs and failure modes, showing how you'd handle edge cases and ensure reliability.
Pro tip: Proactively discuss idempotency and rate limiting early, as they are critical for preventing duplicate accounts and abuse, and demonstrate you think about production readiness from the start.
Ask about expected user volume, regional requirements, compliance (e.g., GDPR, CCPA), and integration points. This ensures your design aligns with business needs and constraints.
Define RESTful endpoints for signup, verification, and login. Outline the user data model with fields like email, phone, password hash, status, and timestamps, considering normalization and indexing.
Explain input validation (format, length, sanitization), password storage (bcrypt/Argon2 with salt), and verification flows (email/SMS with tokens). Include anti-abuse measures like rate limiting, CAPTCHA, and disposable email detection.
Discuss integration with auth services (e.g., OAuth, JWT), downstream services (e.g., user profile, notifications), and data store choices (SQL for transactions, NoSQL for scale, caching).
Describe horizontal scaling, regional deployments, data replication, and failover strategies. Enumerate failure modes (e.g., duplicate signups, verification bypass, DDoS) and mitigations.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.