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Posted Jun 10, 2025

Paytm Backend Developer Interview: Technical Challenges and System Design

Backend DeveloperatPaytm
I interviewed for a Backend Developer role at Paytm, a prominent fintech startup in India. The interview process was comprehensive and consisted of multiple stages designed to assess technical skills and problem-solving abilities. The process began with an online coding assessment that tested algorithmic problem-solving skills, followed by technical interviews focusing on system design and coding challenges. The interview journey started with an online test that required implementing an LRU (Least Recently Used) cache, which tested my understanding of data structures and algorithmic efficiency. The subsequent technical interviews delved deeper, with a focus on system design challenges. The most challenging part was the system design interview, where I was asked to design a payment gateway with scalability considerations, which required demonstrating knowledge of distributed systems, transaction management, and architectural design principles. Overall, the interview process was rigorous and demanded a strong foundation in backend development, system design, and problem-solving skills. While the interviews were challenging, they provided an excellent opportunity to showcase technical expertise and system design thinking in a real-world fintech context.
Backend Development
System Design
Fintech
Technical Interview
Algorithmic Problem Solving

Related Interview Questions

Implement an LRU cache

An LRU (Least Recently Used) cache implementation tests understanding of data structure design, algorithmic efficiency, and cache management. Typically involves creating a data structure that maintains both fast access and a mechanism to remove the least recently used items when the cache reaches its capacity. Common implementation involves using a combination of a hash map and a doubly linked list to achieve O(1) time complexity for get and put operations.

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Design a URL shortener

A system design problem that evaluates ability to create a scalable service for generating and managing shortened URLs. Requires considering key aspects like unique ID generation, URL mapping, redirection mechanism, and potential scalability challenges. Typical solution involves using a combination of base62 encoding, distributed ID generation, and efficient storage mechanisms.

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Design a payment gateway with scalability considerations

A complex system design challenge that tests understanding of financial transaction systems, distributed architecture, security, and scalability. Requires designing a robust system that can handle high transaction volumes, ensure transaction integrity, manage concurrent users, implement security protocols, and provide fault tolerance. Key considerations include transaction processing, payment routing, fraud detection, and horizontal scaling strategies.

System Design
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Fintech
Scalability
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