Stripe PostgreSQL Interview Questions 2026
Published July 22, 2026 · Updated July 22, 2026
5 real PostgreSQL interview questions asked at Stripe. Upvoted by engineers who cleared the loop. Covers System Design, Technical rounds.
5 questions
262 engineers asked
334 upvotes
Company: Stripe
Technology: PostgreSQL
All PostgreSQL Questions Asked at Stripe
Stripe
Hard
System Design round
KafkaPostgreSQLDistributed Systems
Design Stripe's webhook delivery system.
Stripe sends millions of webhooks per day to customer endpoints that can be slow, down, or buggy.
Cover: at-least-once delivery guarantees, retry with exponential backoff, ordering guarantees (or lack thereof), how to handle a customer endpoint that is down for 24h, and the dead-letter strategy.
↑ 79 upvotes · 77 engineers asked this · SDE2
Stripe
Hard
Technical round
PostgreSQLRESTDistributed Systems
Explain how Stripe handles exactly-once payment processing.
A customer clicks "Pay" twice in quick succession. How does Stripe prevent double-charging?
Walk through idempotency keys in the API, database-level constraints, and how the client should handle the case where the first request times out.
↑ 67 upvotes · 65 engineers asked this · SDE2
Stripe
Hard
System Design round
Distributed SystemsKafkaPostgreSQL
Design Stripe's fraud detection system. For every payment, you must decide accept/decline in under 100ms using hundreds of signals. Cover: feature engineering, real-time ML scoring, rule engine, and how you minimise false positives (declined legitimate payments).
↑ 68 upvotes · 44 engineers asked this · SDE2
Stripe
Medium
Technical round
RESTPostgreSQLJava
Explain the difference between synchronous and asynchronous API design using Stripe as an example. When does a charge complete immediately vs require a webhook? How do you handle the intermediate "pending" state in your database?
↑ 57 upvotes · 36 engineers asked this · SDE1
Stripe
Hard
System Design round
PostgreSQLKafkaDistributed Systems
Design Stripe's subscription billing system (Stripe Billing). Customers are charged on recurring intervals (monthly/annual) in different currencies, with proration for plan upgrades. Cover: invoice generation, dunning for failed payments, and SCA (Strong Customer Authentication) compliance.
↑ 63 upvotes · 40 engineers asked this · SDE2
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Frequently asked questions
Design Stripe's webhook delivery system.
Design Stripe's webhook delivery system.
Stripe sends millions of webhooks per day to customer endpoints that can be slow, down, or buggy.
Cover: at-least-once delivery guarantees, retry with exponential backoff, ordering guarantees (or lack thereof), how to handle a customer endpoint that is down for 24h, and the dead-letter strategy.
Explain how Stripe handles exactly-once payment processing.
Explain how Stripe handles exactly-once payment processing.
A customer clicks "Pay" twice in quick succession. How does Stripe prevent double-charging?
Walk through idempotency keys in the API, database-level constraints, and how the client should handle the case where the first request times out.
Design Stripe's fraud detection system. For every payment, you must decide accept/decline in under 100ms using hundreds of signals. Cover: feature engineering, real-time ML scoring, rule engine, and how you minimise false positives (declined legitimate payments).
Design Stripe's fraud detection system. For every payment, you must decide accept/decline in under 100ms using hundreds of signals. Cover: feature engineering, real-time ML scoring, rule engine, and how you minimise false positives (declined legitimate payments).
Explain the difference between synchronous and asynchronous API design using Stripe as an example. When does a charge complete immediately vs require a webhook? How do you handle the intermediate "pending" state in your database?
Explain the difference between synchronous and asynchronous API design using Stripe as an example. When does a charge complete immediately vs require a webhook? How do you handle the intermediate "pending" state in your database?
Design Stripe's subscription billing system (Stripe Billing). Customers are charged on recurring intervals (monthly/annual) in different currencies, with proration for plan upgrades. Cover: invoice generation, dunning for failed payments, and SCA (Strong Customer Authentication) compliance.
Design Stripe's subscription billing system (Stripe Billing). Customers are charged on recurring intervals (monthly/annual) in different currencies, with proration for plan upgrades. Cover: invoice generation, dunning for failed payments, and SCA (Strong Customer Authentication) compliance.