PhonePe Interview Questions 2026
Published July 22, 2026 · Updated July 22, 2026
8 real interview questions asked at PhonePe. Covers System Design, Behavioral, Domain, Redis / Expiry. Reported by engineers who went through the PhonePe process.
8 questions
281 engineers asked
416 upvotes
System Design (3)
PhonePe
Hard
System Design round
KafkaDistributed SystemsPostgreSQL
Design PhonePe's UPI transaction system to handle 1 billion transactions per day.
Cover: request routing to the correct bank, NPCI integration, handling duplicate transactions, consistency vs availability trade-offs, and how you build a reliable audit trail for regulatory compliance.
↑ 89 upvotes · 89 engineers asked this · SDE2
PhonePe
Hard
System Design round
Distributed SystemsKafkaRedis
Design PhonePe's switch - the internal routing layer that forwards UPI requests to the correct bank. It must be highly available (99.999%), handle 50k TPS, and complete each request within 30 seconds (NPCI timeout). Cover: circuit breakers, retries, and bank-specific timeouts.
↑ 66 upvotes · 43 engineers asked this · SDE2
PhonePe
Hard
System Design round
KafkaPostgreSQLRedis
Design PhonePe's merchant settlement system. Thousands of merchants receive daily settlements of their collected payments minus fees. How do you compute net payables, batch into bank transfers, and provide a reconciliation report?
↑ 54 upvotes · 33 engineers asked this · SDE2
Behavioral (2)
PhonePe
Easy
HR round
Why do you want to work at a fintech company specifically?
Describe a situation where you had to learn a domain (payments, banking, compliance) quickly to solve a technical problem. What was your approach?
↑ 44 upvotes · 16 engineers asked this · SDE1
PhonePe
Medium
HR round
Tell me about a time you had to debug a critical production issue affecting financial transactions. What was your systematic approach, how did you communicate during the incident, and what was the resolution?
↑ 47 upvotes · 29 engineers asked this · SDE2
Domain (2)
PhonePe
Hard
Technical round
PostgreSQLRedisJava
Explain how PhonePe handles transaction deduplication. A user taps "Pay" twice due to network lag. The same debit must not happen twice. Walk through idempotency at the API level, database level, and bank integration level.
↑ 55 upvotes · 35 engineers asked this · SDE2
PhonePe
Medium
Technical round
Distributed SystemsJava
What is eventual consistency and why is it acceptable for some PhonePe features but not others? Give examples: where strong consistency is mandatory (debit/credit) vs where eventual consistency is fine (notification delivery, analytics).
↑ 43 upvotes · 26 engineers asked this · SDE1
Redis / Expiry (1)
PhonePe
Medium
Technical round
2-5 yearsRedis
You use Redis to cache OTPs with a 5-minute TTL. How does Redis actually expire keys internally — does it scan the whole keyspace on a timer?
↑ 18 upvotes · 10 engineers asked this · SDE2
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Frequently asked questions
Design PhonePe's UPI transaction system to handle 1 billion transactions per day.
Design PhonePe's UPI transaction system to handle 1 billion transactions per day.
Cover: request routing to the correct bank, NPCI integration, handling duplicate transactions, consistency vs availability trade-offs, and how you build a reliable audit trail for regulatory compliance.
Why do you want to work at a fintech company specifically?
Why do you want to work at a fintech company specifically?
Describe a situation where you had to learn a domain (payments, banking, compliance) quickly to solve a technical problem. What was your approach?
Design PhonePe's switch - the internal routing layer that forwards UPI requests to the correct bank. It must be highly available (99.999%), handle 50k TPS, and complete each request within 30 seconds (NPCI timeout). Cover: circuit breakers, retries, and bank-specific timeouts.
Design PhonePe's switch - the internal routing layer that forwards UPI requests to the correct bank. It must be highly available (99.999%), handle 50k TPS, and complete each request within 30 seconds (NPCI timeout). Cover: circuit breakers, retries, and bank-specific timeouts.
Explain how PhonePe handles transaction deduplication. A user taps "Pay" twice due to network lag. The same debit must not happen twice. Walk through idempotency at the API level, database level, and bank integration level.
Explain how PhonePe handles transaction deduplication. A user taps "Pay" twice due to network lag. The same debit must not happen twice. Walk through idempotency at the API level, database level, and bank integration level.
Tell me about a time you had to debug a critical production issue affecting financial transactions. What was your systematic approach, how did you communicate during the incident, and what was the resolution?
Tell me about a time you had to debug a critical production issue affecting financial transactions. What was your systematic approach, how did you communicate during the incident, and what was the resolution?