Criteo

Senior Software Engineer

Software EngineerL4Medium to Hard

The Senior Software Engineer (L4) interview process at Criteo is designed to assess a candidate's technical expertise, problem-solving abilities, system design skills, and cultural fit. It typically involves multiple rounds, including technical interviews, a system design interview, and a behavioral/managerial interview. The process aims to identify individuals who can contribute significantly to complex projects, mentor junior engineers, and uphold Criteo's engineering standards.

Rounds

3

Timeline

~14 days

Experience

4 - 10 yrs

Salary Range

US$110000 - US$150000

Total Duration

150 min

Overall Evaluation Criteria

Technical Skills

Problem-solving skills
Algorithmic thinking
Coding proficiency and best practices
Data structures knowledge
System design capabilities
Scalability and performance considerations
Communication skills
Teamwork and collaboration
Cultural fit and alignment with Criteo values

System Design

Ability to design robust and scalable systems
Understanding of trade-offs in system design
Knowledge of distributed systems principles
Experience with relevant technologies (databases, messaging queues, caching)

Behavioral and Leadership

Behavioral examples demonstrating leadership
Ability to mentor junior engineers
Experience with project management and delivery
Adaptability and learning agility
Alignment with Criteo's mission and values

Preparation Tips

1Review fundamental computer science concepts (data structures, algorithms, operating systems, databases).
2Practice coding problems regularly, focusing on efficiency and clarity.
3Study system design principles and common architectural patterns.
4Prepare specific examples from your past experience to answer behavioral questions using the STAR method (Situation, Task, Action, Result).
5Research Criteo's products, services, and company culture.
6Understand the technologies commonly used at Criteo (e.g., Java, Python, Scala, distributed systems, cloud platforms).
7Prepare thoughtful questions to ask the interviewer about the role, team, and company.

Study Plan

1

Data Structures and Algorithms Fundamentals

Weeks 1-2: Data Structures & Algorithms (Medium LeetCode).

Weeks 1-2: Focus on core data structures (Arrays, Linked Lists, Trees, Graphs, Hash Tables) and algorithms (Sorting, Searching, Dynamic Programming, Graph Traversal). Practice implementing these efficiently and analyze their time/space complexity. Solve LeetCode problems tagged 'Medium'.

2

System Design

Weeks 3-4: System Design Principles & Practice.

Weeks 3-4: Deep dive into system design concepts. Study topics like load balancing, caching, database scaling (sharding, replication), message queues, microservices architecture, and API design. Review common system design interview questions and practice designing systems like Twitter feed, URL shortener, etc.

3

Behavioral and Cultural Fit

Week 5: Behavioral Preparation (STAR Method) & Company Research.

Week 5: Prepare for behavioral questions. Reflect on your past projects and experiences, identifying examples that showcase leadership, teamwork, problem-solving, and conflict resolution. Structure these using the STAR method. Research Criteo's values and prepare to articulate how you align with them.

4

Final Preparation

Week 6: Mock Interviews & Final Review.

Week 6: Mock interviews, focusing on both technical and behavioral aspects. Refine your explanations and practice articulating your thought process clearly. Review any weak areas identified during practice.

Commonly Asked Questions

Describe a time you had to deal with a difficult stakeholder. How did you handle it?
How would you design a system to handle real-time bidding in advertising?
What are the trade-offs between monolithic and microservices architectures?
Write a function to find the k-th largest element in an unsorted array.
Explain the concept of eventual consistency.
Tell me about a project you are particularly proud of and your role in it.
How do you approach debugging a complex distributed system?
Design an API for a simple e-commerce product catalog.
What strategies do you use to ensure code quality and maintainability?
How do you stay updated with new technologies and industry trends?

Location-Based Differences

Paris

Interview Focus

Strong emphasis on practical problem-solving and coding proficiency.System design questions often relate to Criteo's ad-tech domain.Behavioral questions focus on collaboration and impact within a team.

Common Questions

How would you design a URL shortener service?

Discuss a challenging technical problem you solved recently.

Explain the trade-offs between SQL and NoSQL databases.

How do you handle concurrency in your applications?

Describe your experience with cloud platforms (AWS, GCP, Azure).

Tips

Familiarize yourself with Criteo's core business and technologies.
Practice coding problems on platforms like LeetCode, focusing on medium to hard difficulty.
Prepare detailed examples for behavioral questions using the STAR method.
Research common system design patterns and be ready to discuss trade-offs.

New York

Interview Focus

Greater emphasis on distributed systems and scalability.System design questions may be more abstract and theoretical.Behavioral questions might explore leadership potential and cross-functional collaboration.

Common Questions

Design a distributed caching system.

How would you scale a social media feed?

Explain the CAP theorem and its implications.

What are the principles of RESTful API design?

Describe your experience with microservices architecture.

Tips

Deep dive into distributed systems concepts and algorithms.
Be prepared to whiteboard complex system designs.
Highlight experiences with large-scale data processing and real-time systems.
Understand Criteo's global presence and how that impacts engineering decisions.

Process Timeline

1
Coding and Algorithms Round45m
2
System Design Round60m
3
Behavioral and Team Fit Round45m

Interview Rounds

3-step process with detailed breakdown for each round

1

Coding and Algorithms Round

Coding problems focusing on data structures and algorithms.

Technical Phone Screen / Online AssessmentMedium
45 minSoftware Engineer

This initial technical round focuses on assessing your core programming skills and problem-solving abilities. You will be asked to solve one or two coding problems, typically involving data structures and algorithms. The interviewer will evaluate how you approach the problem, your thought process, the efficiency of your solution, and the clarity of your code. Expect to write code in a shared editor or on a whiteboard.

What Interviewers Look For

Logical thinkingAbility to translate requirements into codeUnderstanding of fundamental CS conceptsClean and efficient coding style

Evaluation Criteria

Problem-solving approach
Correctness of the solution
Code efficiency (time and space complexity)
Code readability and maintainability
Communication of thought process

Questions Asked

Given a binary tree, invert the tree.

Data StructuresRecursionTree

Find the first non-repeating character in a string.

StringsHash TableArrays

Implement a function to check if a linked list has a cycle.

Linked ListPointersAlgorithms

Preparation Tips

1Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte.
2Focus on understanding the time and space complexity of your solutions.
3Be prepared to explain your approach before you start coding.
4Practice thinking out loud as you solve problems.

Common Reasons for Rejection

Inability to articulate thought process clearly.
Poor coding practices (e.g., inefficient code, lack of error handling).
Fundamental misunderstanding of data structures or algorithms.
Difficulty in solving even basic coding problems.
2

System Design Round

Design a scalable and reliable system for an open-ended problem.

System Design InterviewHard
60 minSenior Software Engineer / Architect

This round assesses your ability to design complex, scalable, and reliable systems. You'll be given an open-ended problem (e.g., design a service like Twitter, a URL shortener, or a notification system) and expected to discuss various aspects, including data modeling, API design, component interactions, scalability strategies, and potential bottlenecks. The focus is on your thought process, trade-off analysis, and ability to handle ambiguity.

What Interviewers Look For

Architectural thinkingExperience with large-scale systemsAbility to break down complex problemsKnowledge of various system components (databases, caches, queues)Pragmatic approach to design

Evaluation Criteria

Ability to design scalable and reliable systems
Understanding of distributed systems concepts
Consideration of trade-offs
Clarity of design and communication
Handling of edge cases and failure scenarios

Questions Asked

Design a distributed key-value store.

System DesignDistributed SystemsDatabases

Design a rate limiter for an API.

System DesignAPIsAlgorithms

Design a system to count unique visitors to a website in real-time.

System DesignBig DataScalability

Preparation Tips

1Study common system design patterns and architectures.
2Practice designing systems for scale and reliability.
3Be prepared to discuss trade-offs between different approaches.
4Think about data storage, caching, load balancing, and fault tolerance.
5Ask clarifying questions to define the scope and requirements.

Common Reasons for Rejection

Lack of depth in system design knowledge.
Inability to handle ambiguity in requirements.
Poor consideration of trade-offs (scalability, reliability, cost).
Not asking clarifying questions.
Focusing too much on implementation details too early.
3

Behavioral and Team Fit Round

Assesses teamwork, communication, and cultural fit through behavioral questions.

Behavioral / Managerial InterviewMedium
45 minHiring Manager / Senior Team Member

This round focuses on your behavioral competencies, teamwork abilities, and overall fit with Criteo's culture. You'll be asked questions about your past experiences, how you handle challenges, work with others, and your career aspirations. The interviewer aims to understand your working style, your ability to collaborate, and how you might contribute to the team and company.

What Interviewers Look For

Team player attitudeCommunication clarityOwnership and accountabilityGrowth mindsetCultural alignment

Evaluation Criteria

Collaboration and teamwork skills
Problem-solving approach in team settings
Leadership potential
Adaptability and learning agility
Alignment with Criteo's culture and values

Questions Asked

Tell me about a time you disagreed with a teammate. How did you resolve it?

BehavioralTeamworkConflict Resolution

Describe a situation where you had to learn a new technology quickly.

BehavioralLearningAdaptability

How do you prioritize your work when you have multiple competing deadlines?

BehavioralTime ManagementPrioritization

Preparation Tips

1Prepare specific examples using the STAR method for common behavioral questions.
2Reflect on your strengths and weaknesses.
3Think about your motivations for joining Criteo.
4Be ready to discuss your career goals and how this role fits into them.
5Show enthusiasm and genuine interest in the company and the role.

Common Reasons for Rejection

Lack of self-awareness.
Inability to provide specific examples.
Poor communication or interpersonal skills.
Mismatch with team culture or company values.
Lack of enthusiasm or engagement.

Commonly Asked DSA Questions

Frequently asked coding questions at Criteo

View all
Two SumEASYValid ParenthesesEASYSearch in Rotated Sorted ArrayMEDIUMMerge Sorted ArrayEASYIntersection of Two ArraysEASYRansom NoteEASYRandom Pick with WeightMEDIUMFlood FillEASY