Grubhub Software Engineer II - Backend Interview Guide

If you’re preparing for the Software Engineer II - Backend position at Grubhub, here’s a detailed guide based on recent interview experiences. This will help you understand the entire interview process, the types of questions you can expect, and how to approach them.

Interview Process Overview

The Grubhub interview process typically follows several key stages: initial screening, coding assessments, system design interviews, and behavioral interviews. Here’s a breakdown:

1. Initial Screening:

Recruiter Call:

The first step is usually a call from a recruiter. This interview is not highly technical, but it’s essential for understanding your motivations, career trajectory, and alignment with the role. The recruiter will ask you about your past experience, particularly focusing on your backend development skills, technologies you’ve worked with (e.g., Java, Python, Node.js), and your familiarity with cloud infrastructure (AWS, GCP).

• Example Question: “Can you describe a challenging backend system you built in your previous role?“

2. Technical Screening:

If the recruiter call goes well, you’ll move on to a technical screening, usually conducted over a coding platform like HackerRank or CoderPad. You’ll be given coding challenges that focus on data structures and algorithms. These problems typically test your problem-solving skills and how you optimize solutions.

• Example Question: “Given a large dataset of user activities, how would you design a system to process and analyze this data in real time?” This tests your understanding of distributed systems and your ability to think about scalability.

3. Coding Assessment:

Online Coding Challenge:

Grubhub’s coding assessment often includes a series of algorithmic problems that need to be solved within a specific time frame. These challenges assess your knowledge of algorithms, data structures, and time complexity.

• Example Coding Problems:
  • Problem 1: “Write a function to find the longest substring without repeating characters.”
  • Problem 2: “Design an API that returns the most popular food items ordered in the last week.”

Tip: Focus on optimizing your solutions for both time and space complexity. Grubhub will be keen to see if you can write efficient, scalable code.

4. System Design Interview:

One of the most important parts of the interview for a backend engineering role is the system design interview. Here, you’ll be asked to design complex backend systems that are scalable, reliable, and optimized for performance. These systems might include a food delivery service or a restaurant recommendation engine.

• Example System Design Questions:
  • Problem 1: “Design a scalable system for processing and dispatching food delivery orders in real-time. How would you ensure the system is fault-tolerant and handles peak traffic?”
  • Problem 2: “Design a service that tracks user behavior on the Grubhub platform and provides personalized food recommendations.”

Key Areas to Focus On:

• Scalability: How would your design handle millions of users or requests per second?
• Fault Tolerance: How would you ensure that the system is highly available even when individual components fail?
• Database Design: Choose the right database (SQL vs NoSQL) based on the use case. For example, a restaurant system might need a NoSQL database for storing orders and a relational database for user accounts.
• Caching: Discuss how you would use caching (e.g., Redis or Memcached) to optimize performance.

5. Behavioral Interview:

The behavioral interview is an opportunity for Grubhub to evaluate your cultural fit within the company. Expect questions that explore how you work within a team, deal with conflict, and handle challenges.

• Example Behavioral Questions:
  • “Tell me about a time you faced a difficult technical challenge. How did you approach it?”
  • “Describe a situation where you had to collaborate with a cross-functional team. How did you ensure good communication?”
  • “How do you prioritize your tasks when you have multiple deadlines?“

6. Final Onsite or Virtual Interviews:

The final round often consists of multiple technical and behavioral interviews. You might have two or three rounds, each lasting about 45 minutes to an hour. These interviews are designed to assess your deep technical knowledge and whether you’re a good cultural fit for the team.

• Coding Interview: Another coding challenge, either whiteboard or using an online platform, focused on algorithms or backend-related tasks.
• System Design Interview: A deeper dive into your system design capabilities, focusing on high-level architecture and design choices.
• Behavioral Interview: Further discussion on your past experiences, team collaboration, and problem-solving skills.

Key Areas Grubhub Focuses On

1. Backend Engineering Skills:

Grubhub expects candidates to be proficient in backend technologies such as Java, Python, or Node.js. Make sure you’re comfortable working with APIs, databases (both SQL and NoSQL), and message queues like Kafka or RabbitMQ.

• Example Question: “How would you handle authentication in a microservices architecture?“

2. Distributed Systems:

As Grubhub operates at scale, understanding how to build and maintain distributed systems is crucial. You’ll need to know how to design systems that can handle high traffic and ensure data consistency, availability, and partition tolerance (CAP theorem).

• Example Question: “How would you ensure consistency across distributed services in a food delivery system?“

3. Database Design & Query Optimization:

Be prepared to discuss different database solutions (SQL vs NoSQL) and how to optimize queries, especially when working with large datasets.

• Example Question: “How would you design the database for an order management system?“

4. Cloud Infrastructure:

Grubhub uses cloud services like AWS or GCP, so having a solid understanding of cloud architecture, serverless functions, containers (Docker), and Kubernetes will be beneficial.

• Example Question: “How would you manage the deployment of microservices in a Kubernetes cluster?“

5. Testing and Debugging:

Expect to discuss how you would ensure the reliability of backend systems. This could involve unit testing, integration testing, and end-to-end testing strategies.

• Example Question: “What testing strategies would you use to ensure that your APIs are reliable and bug-free?”

Tips for Preparation

• Practice Coding: Make sure you’re comfortable with solving algorithm problems on platforms like LeetCode, HackerRank, or CodeSignal. Focus on data structures like arrays, trees, graphs, and hash maps.
• Review System Design: Study common design patterns and practice designing systems like order processing, recommendation engines, and chat services. Books like “Designing Data-Intensive Applications” by Martin Kleppmann can be helpful.
• Understand Grubhub’s Business: Familiarize yourself with Grubhub’s business model, challenges, and technology stack. This will help you provide contextually relevant answers during the interview.
• Behavioral Preparation: Use the STAR method (Situation, Task, Action, Result) to structure your answers for behavioral questions. This helps you stay concise and focused on key achievements.

Example Interview Questions Recap

Coding:

• “Write a function to reverse a linked list.”
• “How would you implement a rate-limiting service for an API?”

System Design:

• “Design a system to recommend the most popular dishes in real-time based on user feedback.”
• “How would you design a microservices-based architecture for Grubhub’s food delivery service?”

Behavioral:

• “Tell me about a time when you disagreed with a teammate. How did you handle it?”
• “Describe a situation where you had to debug a production issue under tight deadlines.”