System designHardsd-g696

Subject Push notification gateway networkingLevel Senior–Staff~45 minCommon in Networking & APIs · Distributed systems interviewsIndustries Technology, Telecom

Question

Design a push-notification gateway that delivers to 300M devices across APNs (iOS) and FCM (Android) at a peak burst of 1M notifications/sec (e.g. a breaking-news fan-out). You must respect provider connection limits and rate limits, dedupe, handle invalid/expired device tokens, and give product teams accurate delivery feedback. What does the pipeline look like and what's the hard part?

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

Loading whiteboard…

Run or narrate your approach, then ask the coach.