System Design: End-to-End Project Walkthrough

Provide a structured walkthrough of a recent project you led end-to-end. Organize your answer using the sections below. Be concise, concrete, and quantify where possible.

1) Problem Statement

• What business/user problem were you solving?
• Baseline pain and measurable goals (latency, cost, reliability, adoption, etc.).

2) Requirements

• Functional requirements.
• Non-functional requirements (throughput, latency SLOs, availability, durability, cost targets, privacy/compliance, SLAs).

3) Architecture

• Components/services and their responsibilities.
• Data stores and data flow.
• External/internal APIs (include example requests/responses).

4) Key Design Decisions and Trade-offs

• Major choices (protocols, data formats, storage engines, consistency model, partitioning, caching, idempotency).
• Trade-offs you considered and why you picked the final approach.

5) Alternatives Evaluated

• 2–3 plausible alternatives with pros/cons and rough cost/complexity comparisons.

6) Scaling Considerations

• Partitioning/sharding strategy, backpressure, rate limiting, hot-spot avoidance.
• Indexing/aggregation strategies. Horizontal vs. vertical scaling.

7) Data Model

• Core entities, schemas, and relationships.
• Partitioning and retention/TTL strategy.
• Schema evolution approach.

8) Dependencies

• Third-party services, internal platforms, libraries, and how they influenced the design.

9) Operational Concerns

• Observability (metrics, logs, traces), alerting, runbooks.
• Deployments, canaries, rollbacks, migrations/backfills, feature flags.

10) Measuring Success

• KPIs/SLOs you tracked and the actual results.

11) Failure/Bottleneck Deep Dive

• One significant failure or bottleneck.
• How you detected, debugged, and mitigated it.

12) V2 Improvements

• What you would change next: architecture, tooling, process, or product.