Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
Summary
I shared my preparation and interview experiences for senior and staff level roles across several companies, including detailed system design and coding questions I faced and how I approached them.
Full Experience
Prep
- DSA: LeetCode Premium, company‑wise tagged questions.
- HLD: Jordan / Hello Interview, plus previously asked questions. Went deep into how things like Kafka work internally.
- LLD: Brushed up basics, built solutions myself and reviewed them with AI.
- LinkedIn premium (not useful), referrals are the best way to get shortlisted.
Interview Experiences
Licious — SDE 3
- Machine coding: Build an API following best practices.
- F2F round: Java and Spring Boot basics (unprepared).
FirstClub — Tech Lead
- Assignment: Build a rewards microservice.
- HR ghosted after submission.
Walmart — Senior Engineer (hiring drive)
- Online test: 2 LeetCode medium questions (HackerRank) + theoretical Java questions.
- DSA round: Easy‑to‑medium question solvable using a HashMap.
- LLD round: Design a hospital management system – class diagram, small implementation, discussion on logic.
- System design round: Design Google Drive.
- Cleared all rounds but stopped the process because the Staff loop was also cleared.
Walmart — Staff Engineer
- DSA round: 2 LeetCode medium questions on HackerRank.
- LLD round: Design an access control layer for a SaaS tool (cover RBAC, ABAC, ReBAC, data modelling).
- System design round: Design a live collaboration tool like Google Docs (discuss OT, CRDTs, class design).
- AI/HR round: Discussed AI tools and a knowledge‑sharing project.
- Cleared all rounds and received the offer.
ThoughtSpot
- DSA round: LeetCode Hard – median of a stream.
- System design round: Interviewer poorly conducted, but I explained the correct solution.
- Ghosted after the loop.
Amazon — SDE 3
- DSA round: 2 LeetCode medium questions – Jump Game and a straightforward DFS graph traversal.
- LLD round: Design LFU cache with TTL (used composition with a CachingContext handling LFU and TTL eviction policies).
- HLD round: Design a distributed rate limiter with queuing, spare‑capacity sharing, 10k RPS today scaling to 1 M RPS, using Redis cluster, Kafka queues, Lua scripts, and a leasing service.
Oracle Health — IC4
- Round 1: Manager discussion on past projects.
- Round 2: HLD – Design a notification service.
- Round 3: Behavioral questions.
- Round 4: Design the search bar for the AWS console UI (ranking by last used, inverted indexes, fuzzy matching, provisioning and deployment).
Rippling — Senior Software Engineer
- Shortlisted but cancelled interview in favor of Walmart.
Other Senior/Staff roles
- Cleared a few other startups (salary 65‑70 LPA).
Interview Questions (9)
Design Access Control Layer for SaaS Tool
Design an access control layer for a SaaS application covering Role‑Based Access Control (RBAC), Attribute‑Based Access Control (ABAC), and Relationship‑Based Access Control (ReBAC). Include data modelling for permissions in the database and discuss how the layer would enforce policies at runtime.
Live Collaboration Tool like Google Docs
Design a real‑time collaborative document editing service similar to Google Docs. Discuss the algorithms for concurrent editing (Operational Transformation or CRDT), the system components, data storage, and how you would scale to many concurrent users.
Median of a Stream (LeetCode Hard)
Given a stream of integers, design a data structure that supports adding a number and retrieving the median of all elements added so far in O(log n) time per operation.
Jump Game (LeetCode Medium)
Given an array of non‑negative integers where each element represents the maximum jump length from that position, determine if you can reach the last index.
DFS Graph Traversal (LeetCode Medium)
Perform a depth‑first traversal on a given undirected graph and return the order of visited nodes.
Design LFU Cache with TTL
Design a Least Frequently Used (LFU) cache that also supports a Time‑To‑Live (TTL) for each entry. The cache should evict items based on usage frequency while respecting expiration times.
Distributed Rate Limiter
Design a distributed rate‑limiting service for an internal API. Each upstream service has a fixed throughput limit per API key. Requests that exceed the limit should be queued, not rejected, and spare capacity from one service should be usable by another. The system must handle 10k RPS now and scale to 1 M RPS.
Design Search Bar for AWS Console UI
Design the backend for a search bar in the AWS console that lets users search for services. Results should be ranked by recency of use. The design must consider provisioning, deployment, and scaling within Amazon's control plane.
Design Hospital Management System (LLD)
Create a class diagram and a minimal implementation for a hospital management system covering patients, doctors, appointments, and billing.
Preparation Tips
- DSA: Practised LeetCode Premium, focused on company‑tagged problems.
- HLD: Used Jordan / Hello Interview resources, studied internal workings of systems like Kafka.
- LLD: Built solutions from scratch, reviewed with AI, emphasized deep understanding.
- Leveraged LinkedIn Premium for visibility, but relied mainly on referrals.