Stripe Software Engineer Interview Questions

1.Tell me about the last API or developer tool you designed. Walk me through how you made decisions about the interface and what feedback you got from the people who used it.

2.Tell me about a time you built something that other engineers on your team or adjacent teams ended up using regularly. What made it successful for them?

3.Describe a time when you had to choose between building something quick and dirty versus a more thorough solution. What factors did you consider and how did you decide?

4.Walk me through a situation where you realized you were wrong about something technical. How did you discover it and what did you do next?

5.Tell me about a technical design or architecture decision you had to explain in writing to people outside your immediate team. How did you structure that communication?

6.Describe a project where you had to push back on scope or timeline because you felt the proposed approach would create too much technical debt. How did that conversation go?

7.Write a function that validates a credit card number using the Luhn algorithm and returns both whether it's valid and what card brand it is.

8.Implement a rate limiter that can handle different limits for different API keys and should work across multiple server instances.

9.Our payments API currently returns a 500 error when a card is declined, but we want to return structured error details to help developers handle different decline reasons. How would you approach this migration?

10.You need to store payment method data that's PCI compliant but also enable fast lookups by multiple fields like customer_id, brand, and last_four. What's your storage and indexing strategy?

11.You're implementing a webhook delivery system that needs to handle millions of events per hour with guarantees that each event reaches the merchant exactly once. Walk me through your design.

12.Our fraud detection system flags legitimate transactions as suspicious, causing good customers to get declined. How would you design an experiment to test a new ML model that might reduce false positives?

13.Design a payment routing system that can switch between different payment processors in real-time based on success rates. You're handling 10,000 transactions per second and need to make routing decisions in under 50ms.

14.Design the notification system for Stripe Connect that needs to deliver webhooks to hundreds of thousands of platforms, each with different reliability characteristics. Some platforms go down for hours, others have rate limits.

15.Design the data pipeline for Stripe Radar that ingests billions of payment events daily and needs to provide fraud scores within 100ms of a transaction attempt. How do you handle the machine learning model updates?

16.You're building the ledger system for Stripe Treasury that tracks every balance change for millions of accounts. Design this to handle 50,000 transactions per second while maintaining perfect consistency and enabling real-time balance queries.

17.Design Stripe's internal configuration service that every API request hits to determine feature flags, rate limits, and regional routing rules. It needs 99.99% availability even when its own database is completely down.

18.Design the reconciliation system for Stripe Billing that needs to match millions of subscription charges against actual payment processor responses daily, handling cases where payments succeed but our database updates fail.

19.Tell me about a time you had to convince a skeptical engineer or team to adopt a new tool or process you believed in. How did you approach that conversation?

20.Describe a situation where you had to coordinate work across multiple teams or services to ship a feature. What made that coordination challenging?

21.Walk me through a time when you had to maintain or improve a critical system that other teams depended on. How did you balance their needs with your team's other priorities?

22.Tell me about a time you identified a systemic issue that was affecting multiple engineers or teams. How did you drive a solution without being the most senior person involved?

23.Describe a time you had to make a technical decision where you knew it would create short-term friction for other engineers but believed it was the right long-term choice. How did you handle that situation?

24.Tell me about a time you noticed that engineering practices or code quality were slipping on your team or in an area you cared about. How did you address it?

25.Estimate how many API calls Stripe processes per day and walk me through your reasoning.

26.You notice that API response times for Stripe Connect platform partners increased by 20ms last week. No code changes were deployed. How would you investigate this?

27.Estimate the cost impact if Stripe's payment success rate dropped from 98% to 97%. What factors would you consider?

28.A large Stripe Atlas customer reports that their new company incorporation is stuck in pending state for 3 weeks. Walk me through how you'd diagnose what's happening.

29.Estimate how much computing cost Stripe could save per year by reducing webhook delivery retry attempts from 10 to 8 for failed deliveries.

30.Stripe Billing shows that monthly subscription renewal rates dropped 2% this month, but we haven't changed any billing logic. Walk me through your investigation approach.