Software Engineer at Razorpay

How it went

What they would tell you

How to prepare

Round by round

1. 1

   Technical Assessment(Online Coding Test)90 min

   This round tested problem-solving skills but with a practical twist, not just pure algorithms but problems you could see in a payments backend. The questions required thinking about real-world constraints and designing efficient solutions. Questions & Approach: Detect Fraudulent Transactions

   • Approach: I suggested a sliding window approach that tracks the number of transactions per user within a time frame. Using Redis for caching transaction data seemed natural for speed. The idea was to flag any sudden spike beyond a threshold as suspicious. Design a Concurrent LRU Cache

   • Approach: I combined a HashMap and Doubly Linked List to maintain order and constant-time access. To make it thread-safe, I talked about using Java’s ConcurrentHashMap and synchronizing operations to handle concurrent access without locking the whole cache.

2. 2

   System Design120 min

   The system design round was challenging but engaging. I was asked to design a payment reconciliation system, basically matching payment logs with merchant orders reliably. The interviewer really wanted to hear my thought process on data flow, consistency models, and handling failures. Design a Payment Reconciliation System

   • Approach: I proposed using Kafka for log ingestion and Apache Flink for stream processing to handle real-time reconciliation. I preferred eventual consistency to keep the system responsive and suggested exponential backoff retries for failed log processing. We also discussed how to handle out-of-order events.
3. 3

   Low-Level Design90 min

   This round felt very close to real work, I had to design a notification service that supports SMS, email, and push notifications. The focus was on clean design and testability. I also explained how I’d monitor the service in production. Question & Approach: Build a Multi-Channel Notification Service

   • Approach: I used the Strategy Pattern to separate each notification channel’s logic cleanly. For testing, I discussed mocking external APIs so that unit tests don’t depend on actual network calls. I also planned for Prometheus integration to track delivery stats and failures.

What came up