System designMediumsd-g188

Subject EtlLevel Mid–Senior~40 minCommon in Networking & APIs interviewsIndustries Technology, Software development

Question

Design an ETL connector framework that syncs data from ~50 third-party SaaS APIs (CRMs, ticketing, marketing tools) into a customer's warehouse, refreshing every 15 minutes. Each API differs: some paginate by cursor, some by offset, all have different rate limits and occasional 429/5xx, some support incremental ('updated since') and some only full-dump, and some have eventually-consistent reads. Design the extraction framework so syncs are incremental where possible, resumable on failure, respect rate limits, and never silently miss records.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.