HubSpot·Software Engineer·Onsite - System Design / Architecture
Jun 2026
System design round at HubSpot for a software engineer role. The whole thing was built around designing a weather data crawler, which sounds niche but actually covered a lot of ground: scheduling, storage, freshness, retries, the works. Pretty intense for a single session.
- Design a system that crawls hourly weather data from a public provider like the National Weather Service across 10,000 locations and serves it to internal and external consumers.
- How would you handle rate limits and flaky responses from the weather data provider?
- How would you design the storage schema to support both real-time queries and historical analytics?
- How would you guarantee data freshness and handle backfilling missing or late data?
- What monitoring and alerting would you put in place to detect missing or delayed data ingestion?
“This is the core question and it's deceptively wide.” The rest of the author's notes on Software Engineer interview at HubSpot, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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