Design a news feed aggregator

Q: Design a news feed aggregator

This is a System Design interview question from Rippling for Software Engineer roles. View the full question and solution on PracHub.

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Question

System Design Take‑Home: Large-Scale News Aggregator and Personalized Feed

Context

Design a production-ready news aggregation and personalized feed platform that ingests articles from thousands of publishers, updates users’ feeds in near real time, and supports search, topics, and experimentation at scale.

Functional Requirements

Ingest articles from thousands of publishers via RSS, webhooks, and partner APIs.
- Handle publisher rate limits, retries, transient failures, and deduplication.
- Ensure idempotent ingestion and content normalization.
- Support media handling (images/video) and spam/NSFW detection.
Near–real-time updates: end-to-end under 5 seconds from publisher to user feed.
- Provide backfill for missed content/outages.
Personalized, ranked feed per user using signals: followed sources, topics, recency, user engagement.
- Support experimentation (A/B tests, holdouts) for ranking variants and UI.
Implement keyword search and topic/tag pages, including geo and language filters.

Data, Storage, and Indexing

Design hot vs. cold storage, indexing, and caching layers.
Provide core data models and schemas for publishers, articles, users, follows, topics, engagements, experiments, and feeds.

Feed Generation Strategy

Describe pull vs. push and fan‑out‑on‑write vs. fan‑out‑on‑read trade‑offs.
Choose a strategy (or hybrid) and justify it for scale and latency targets.

Reliability and Availability

Multi-region availability with eventual consistency.
Disaster recovery plan and RPO/RTO targets.

Capacity and Cost

Estimate capacity: QPS, throughput, data volumes.
Propose scaling strategies and cost controls.

APIs, Security, and Privacy

Define external and internal APIs, rate limiting, authentication/authorization.
Address user privacy and compliance (GDPR/CCPA): consent, data deletion/export.

Operations

Monitoring, alerting, logging, tracing, and SLOs.
Rollback and incident mitigation strategies.

Rollout and Testing

Phased rollout plan and end‑to‑end testing strategy (including load, chaos, and experiment guardrails).