DoorDash Senior Software Engineer Interview Questions

Behavioral Questions (15)

1. 1.Tell me about someone on your team who was struggling, and what you did to help them succeed.

   easy~3 min

   What interviewers look for

   • Identifies specific struggles the teammate was facing - technical skills, communication, or workload management
   • Describes proactive actions taken to support the teammate - mentoring, pairing, advocating, or adjusting workload
   • Shows genuine care for the person beyond just work deliverables - understanding their career goals or personal challenges
   • Explains the outcome and what the teammate achieved after receiving support

   Likely follow-ups

   • How did you balance helping them with your own deliverables?
   • What did you learn about yourself as a teammate from this experience?

   Company context

   DoorDash's 'Hustle and Heart' principle combines intense work ethic with genuine care for teammates, Dashers, and merchants. The company values engineers who go beyond their individual contributions to lift up others, reflecting the collaborative culture needed to serve three-sided marketplace complexity.

2. 2.Walk me through how you'd design a real-time ETA prediction service that needs to handle millions of orders per day across different restaurant types and delivery zones.

   easy~4 min

   What interviewers look for

   • Mentions geospatial partitioning or sharding by delivery zone to handle scale efficiently
   • Discusses caching strategies for restaurant prep times and historical delivery data using Redis
   • Considers real-time data ingestion from Dashers' GPS locations using Kafka or similar streaming platform
   • Addresses how to handle different restaurant types (fast-food vs sit-down) with varying prep time patterns

   Likely follow-ups

   • How would you handle a scenario where a popular restaurant's kitchen is running 20 minutes behind during dinner rush?
   • What metrics would you track to ensure your ETA predictions are improving consumer satisfaction?

   Company context

   DoorDash's real-time logistics network requires sub-second ETA calculations that directly impact consumer experience and Dasher efficiency. This tests understanding of geospatial systems, real-time data processing, and the operational complexity that defines DoorDash's 'Operate at Speed' principle while balancing the three-sided marketplace.

3. 3.Design a fraud detection system for DoorDash that can identify suspicious orders and Dasher behavior in real-time. How would you handle the challenge of false positives potentially blocking legitimate orders or Dashers from earning?

   easy~3 min

   What interviewers look for

   • Designs a real-time scoring system that can process millions of orders per day with sub-second latency to avoid disrupting the delivery experience
   • Considers the three-sided marketplace impact - protecting consumers from fraudulent charges while ensuring legitimate Dashers aren't unfairly penalized and can continue earning
   • Proposes tiered response mechanisms (soft blocks, manual review queues, gradual restrictions) rather than binary allow/deny decisions

   Likely follow-ups

   • How would you handle a scenario where your fraud system incorrectly flags a large number of Dashers in a specific geographic area?
   • What metrics would you track to ensure your fraud detection isn't disproportionately affecting certain merchant types or neighborhoods?

   Company context

   DoorDash operates a three-sided marketplace where fraud can impact consumers (payment fraud), merchants (fake orders), and Dashers (account takeovers, stolen tips). The company's 'We are One Team' value means fraud systems must consider all stakeholders, while 'Operate at Speed' requires real-time detection that doesn't slow down legitimate transactions in a time-sensitive logistics network.

4. 4.Tell me about a time you had to convince a cross-functional partner outside of engineering to change their approach. What was their initial position, and how did you influence them?

   easy~3 min

5. 5.We noticed a 15% drop in order completion rate during lunch rush yesterday across three major cities. Walk me through how you'd investigate this and what data points you'd look at first.

   easy~3 min

6. 6.Tell me about a time you had to balance competing priorities between different user groups. How did you approach the tradeoffs?

   medium~4 min

7. 7.You're tasked with implementing a feature flag system that can toggle features independently for consumers, Dashers, and merchants. How would you design this to handle DoorDash's scale while ensuring consistent behavior across the three-sided marketplace?

   medium~5 min

8. 8.Walk me through how you'd design the backend systems for DashPass that need to handle subscription billing, benefit eligibility checks across millions of orders daily, and merchant fee calculations. What are the key consistency and availability trade-offs?

   medium~4 min

9. 9.Describe a time when you had to make a technical decision under significant time pressure that affected multiple teams. How did you communicate the decision and manage the fallout?

   medium~4 min

10. 10.Estimate how many additional Dashers DoorDash would need to hire if we expanded to cover rural areas where the average delivery distance is 3x longer than current urban routes.

    medium~4 min

11. 11.Describe the fastest you've ever shipped a critical feature from concept to production. What corners did you cut, and how did you ensure quality?

    hard~5 min

12. 12.Design a system to handle Dasher batching where one Dasher can pick up multiple orders from different restaurants. The system needs to optimize for delivery time, Dasher earnings, and customer satisfaction simultaneously.

    hard~5 min

13. 13.Design a system that can dynamically adjust delivery fees and Dasher pay in real-time based on demand, supply, and order density. How would you ensure transparency for consumers while optimizing for Dasher utilization across different geographic zones?

    hard~5 min

14. 14.Tell me about the most complex technical initiative you've led where you didn't have formal authority over all the engineers involved. How did you drive alignment and execution across teams?

    hard~5 min

15. 15.DoorDash is considering launching a feature where customers can tip Dashers before the order is placed instead of after delivery. Estimate the impact this would have on our key metrics and walk me through your analysis framework.

    hard~5 min