Product Company · Bengaluru
Razorpay focuses on backend systems and payments infrastructure. Interviews are DSA + system design heavy with strong HR culture-fit evaluation.
Process: DSA Screen → Technical × 2 → System Design → HR
What does Razorpay build and what engineering domains are most relevant to their interviews?
Tip: Razorpay builds payment gateway, banking stack (RazorpayX), and lending products. Engineering domains: distributed systems for payment processing, financial data modelling, high-reliability backend (99.99% uptime SLAs), compliance and security (PCI DSS, RBI norms). Show familiarity with these constraints.
How would you design Razorpay's payment processing pipeline to handle 10,000 transactions per second?
Tip: Pipeline: API gateway → idempotency layer (Redis dedup by payment_id) → payment service → bank gateway adapter (async fan-out). State machine: CREATED → PROCESSING → AUTHORIZED → CAPTURED/FAILED. Async callbacks from banks via webhooks, retry with exponential backoff. Message queue (Kafka) for event sourcing the state transitions.
What is idempotency and why is it critical in payment systems?
Tip: Idempotency: calling the same operation multiple times has the same effect as calling it once. In payments: a network retry must not double-charge. Implementation: client sends a unique idempotency key; server stores the response against the key for 24h. Second request with same key returns cached response without re-processing.
Implement a function to validate a credit card number using the Luhn algorithm.
Tip: Luhn: from right, double every second digit; if doubled value > 9, subtract 9. Sum all digits. Valid if total % 10 == 0. This is a real input sanitisation step in payment SDKs. Razorpay's interview tests both the algorithm and your code's readability.
What is a two-phase commit protocol? When is it used in financial systems?
Tip: Two-phase commit (2PC): Phase 1 (Prepare) — coordinator asks all participants to vote yes/no. Phase 2 (Commit) — if all voted yes, commit; else abort. Used in Razorpay when both the merchant account credit and the customer account debit must succeed atomically. Risk: coordinator failure between phases creates blocking.
How would you implement a webhook delivery system that guarantees at-least-once delivery?
Tip: At-least-once: persist event to DB first, then dispatch. On success, mark delivered. On failure, retry with exponential backoff (1s, 2s, 4s… up to 24h). Dead letter queue after N retries. Consumer must be idempotent (Razorpay includes event_id in payloads). Dashboard for manual retry.
Tell me about a time you ensured the reliability of a critical system you built.
Tip: Razorpay's SLA is 99.99% uptime. Show: you designed for failure (timeouts, circuit breakers, fallbacks), added monitoring before launch, wrote runbooks, and handled an incident gracefully. Mention the specific reliability metric you tracked (error rate, p99 latency) and how you improved it.
What is the difference between optimistic and pessimistic locking in databases?
Tip: Pessimistic: acquire lock before read (SELECT FOR UPDATE) — prevents conflicts, but reduces concurrency. Optimistic: read without lock, check version on write (UPDATE WHERE version = X) — high concurrency, but requires retry on conflict. Razorpay uses optimistic locking for payment state transitions to avoid deadlocks at scale.
What is PCI DSS compliance and why does it matter for a payments company?
Tip: PCI DSS (Payment Card Industry Data Security Standard): 12 requirements for companies handling cardholder data. Key rules: never store CVV, encrypt PAN at rest/transit, quarterly vulnerability scans, segmented cardholder data environment. Razorpay is PCI DSS Level 1 certified — interviewers test basic compliance awareness.
How do you approach debugging a production payment failure with no immediate repro?
Tip: Systematic approach: (1) Check distributed traces for the failed payment_id (Jaeger/Zipkin). (2) Check logs for the gateway response code. (3) Check bank API status page. (4) Reproduce with the same gateway + bank combination in staging. (5) If gateway-side issue, alert the partner and trigger failover to alternate gateway.
Razorpay Software Pvt. Ltd. interviews follow a 4-round process. Here is what to expect and how to prepare for each stage.
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