System Design
81 bites tagged System Design — interview questions with model answers, and 60-second explainers.
Tracing a research insight to shipped code
Give insights stable IDs, link them through tickets to commits and feature flags via tool integrations, measure outcome metrics. Traceability across tools.
Architecting a multi-tenant ResearchOps platform
Tenant isolation model, RBAC plus governance and classification, searchable metadata and a taxonomy for cross-team synthesis. Multi-tenant design balancing isolation and sharing.
Automating research participant recruitment and scheduling
Screener intake, eligibility matching, calendar booking, notifications, incentive payout; handle no-shows and idempotency. Workflow system design with third-party integrations.
Designing an in-house A/B testing platform
Config service, deterministic bucketing SDK, metrics pipeline, analysis engine; fix peeking with fixed samples or sequential tests. System design plus statistical rigor.
Move from flat to usage-based billing
Reliable usage capture, idempotent aggregation into billing periods, and reconciliation with the provider. accurate, scalable metering and billing. tallying charges synchronously or ignoring duplicates and late events.
Designing a feature flagging service
Control plane (UI, store, targeting), SDKs that cache flags locally for zero-latency evaluation, streaming/CDN delivery for near-real-time updates, and stale-flag lifecycle tooling. System design for low-latency config delivery and HA.
Design a centralized auto-remediation platform
Event ingestion, a rules engine mapping alerts to playbooks, a sandboxed execution runtime, and guardrails like dry-run, rate limits, and rollback. Self-healing system design.
Setting SLOs across a dependency chain
Serial dependencies multiply, so each backend needs a tighter SLO than the target; mitigate with redundancy, caching, and graceful degradation. Reliability math across dependencies.
Designing an autonomous research-and-report agent
Planner that decomposes goals, short-term scratchpad plus long-term vector memory, structured tool calls, and a reflect-retry loop for error correction. Agent architecture fundamentals.
Relational versus wide-column for a news feed
Relational gives flexible joins but read-time fan-out; Cassandra precomputes per-user feed rows for fast writes-side fan-out. matching data model to feed access patterns. choosing a store without naming the read pattern.
Design a personalized ad copy pipeline
Identify sources, choose batch versus streaming, generate and deliver copy via APIs. end-to-end data pipeline design for personalization. jumping to a model with no ingestion, privacy, or delivery plan.
Architect a developer-portal personalization engine
A user profile of role and level, content tagged with the same taxonomy, a matching/ranking layer, and a rendering pipeline ordering tutorials. rule-based personalization architecture.
Multi-armed bandit vs A/B testing for headlines
Bandits shift traffic toward winners using updated per-arm reward state; A/B holds fixed splits until a fixed-horizon decision. bandits versus A/B and explore/exploit. calling a bandit just an A/B test that ends early.
Manage localized copy across many A/B tests
A keyed versioned string store, a translation workflow with per-locale status, and pooling or hierarchical analysis for small languages. localization plus experimentation at scale.
Design a programmatic SEO landing-page system
Structured data plus templates, genuinely unique per-page data, static build-time generation, quality gates and indexation control. programmatic SEO and thin-content avoidance. near-identical pages that swap one variable.
Design a next-best-article recommender
Content-based on article embeddings, collaborative on behavior, a hybrid blend, popularity or onboarding fallbacks for new users. recommender design and cold start. pure collaborative filtering with no cold-start plan.
Design an active learning loop for detection
Seed-train, score the pool by uncertainty plus diversity, batch to annotators, retrain, repeat. active learning system design. picking only the most uncertain images and getting redundant near-duplicates.
Design real-time multi-object tracking for AV
Fast detector, Kalman motion model, Hungarian association on IoU plus appearance, track lifecycle for occlusions. tracking-by-detection under latency. per-frame detection with no temporal state or ID management.
Design a cashierless retail checkout vision system.
Multi-camera coverage, person tracking and re-ID, product detection plus action recognition for take or return, sensor fusion, edge-cloud split, and failure handling. end-to-end CV system design.
Designing a high-resolution photorealistic face generator
Weigh StyleGAN's fast, controllable style-based synthesis against diffusion's diversity and stable training; handle scale via progressive or multi-resolution synthesis; protect diversity to avoid mode… system design for high-res faces.
Offload long-running tasks from web requests
Enqueue the job to a queue, return immediately, process with separate workers, report status out of band. async background-job architecture. doing the work in the request thread or fire-and-forget threads.
Design a global low-latency database
A distributed store with replicas near users, a tuned consistency level, accepting lag, conflicts, and cross-region cost. multi-region database tradeoffs. promising low latency, strong consistency, and low cost together.
Trace an event from click to analysis
Client SDK captures and batches, a collection endpoint ingests, a stream and ETL enrich and load into a warehouse for analysis. end-to-end understanding of an analytics event pipeline.
How do you fulfill a GDPR erasure request across data stores?
This tests cross-system deletion under GDPR's 30-day SLA. A strong answer maps PII lineage across S3, databases, and analytics; uses soft deletes for backups; and handles dashboards via reprocessing.
Get System Design bites daily.
Five a day, five minutes, offline. With quizzes so it sticks.
Open testing — you’ll join as an early tester.