Senior+ System Design Interview Questions
System design is the round that carries the most weight in a senior+ loop, and it's where senior+ candidates most often pass or fail. These system design questions were reported from senior-level interviews, so they reflect what interviewers actually push on at the senior+ bar: designing for scale, reasoning explicitly about trade-offs, handling failure modes, and driving the conversation instead of waiting to be led. Expect open-ended prompts — design a rate limiter, a news feed, a notification system — where the interviewer probes your bottlenecks and asks you to defend every decision. Each comes with a detailed model answer that walks through requirements, the high-level design, the deep dives, and the trade-offs a strong senior+ answer makes explicit.
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"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
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"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Design a News Feed and Mail Service
Design the following systems: 1. Aggregate news feed Build a service that ingests articles from many publishers, deduplicates and ranks them, and s...
Design a replicated cloud storage service
This question evaluates a candidate's system-design competency in distributed cloud storage, covering metadata/data separation, replication models, re...
Troubleshoot a single-node web outage
This question evaluates operational troubleshooting, root-cause analysis, and resilience design skills for a single-node web server, testing a candida...
Design a collaborative spreadsheet backend
Design a web-based spreadsheet service similar to Google Sheets, with emphasis on backend architecture and data models. Focus areas: - Multiple users ...
Design an ad frequency capping system
This question evaluates a candidate's ability to design scalable, low-latency distributed systems that enforce ad frequency caps across users, devices...
Design a BLE Command Handler
Design a Bluetooth Low Energy (BLE) command handler for an iOS application. The app needs to send commands to a wearable device over BLE. Commands mus...
Design a content processing service
System Design: High-Throughput Content Processing Service Context Design a content processing and moderation service for a large-scale media app. Cont...
Design an At-Most-Once Job Scheduler
This question evaluates a candidate's competency in distributed systems and system design, focusing on at-most-once execution semantics, fault toleran...
Design aggregator for multiple downstream services
This question evaluates system-design and distributed-systems skills, focusing on microservice aggregation, fan-out/fan-in concurrency, fault toleranc...
Design multi-tenant ingestion and processing platform
This question evaluates a candidate's ability to architect scalable, multi-tenant data ingestion and processing platforms, assessing competencies in t...
Scale Digit-Square Convergence Requests
Design a service that receives very high request volume for the digit-square convergence operation. For each request, the input is a positive integer ...
Design Disk-Based Inventory Serving
Design software for a machine that has no SSD storage and only a small amount of RAM. The machine must service inventory requests using spinning disks...
Review an existing architecture for risks
This question evaluates an engineer's ability to perform an architecture review, identifying imminent scalability, reliability, operability, and secur...
Design an exception monitoring system with top‑K
This question evaluates the ability to design a scalable, low-latency exception monitoring system focusing on streaming ingestion, event grouping/fing...
Measure platform success and drive adoption
This question evaluates a candidate's competency in platform leadership, operational metrics, organizational scaling, and driving cross-team adoption ...
Design an Online Minesweeper Platform
This question evaluates competency in designing scalable, low-latency, real-time stateful systems, covering data modeling, API design, persistence, co...
Design a scalable Instagram-like platform
Design a scalable Instagram-like platform Design: Instagram-like Photo/Video Sharing Platform (Technical Screen) Context Design a photo/video sharing ...
Design device telemetry pipeline for real-time and batch
Design a distributed system that ingests telemetry from millions of devices and supports both: - Real-time analytics (near-real-time dashboards/alerts...
Design a Personalized Weekly Deals Service
Design a Personalized Weekly Deals Service Design a service that ingests deals weekly from several pipelines. Each deal has a start and end time and c...
Design a Stateful Outreach Campaign Engine
Design an internal campaign engine that lets an agent select a custom subset of clients and start an outreach campaign for each selected client. For e...