Zalando – Interview Questions

Software Engineer Interviews with Zalando mainly focus on Rest APIs, Java Microservices, Java OOPS, SQL.

Zalando is one of the visa sponsor companies from europe for Software Engineers.

Interview Guide


Screening Round

  • Introduction
  • Technical Questions (Theoritical or Architectural) in details
  • Explain codility code
  • Code review of a Java code file:
    • Functionaly working
    • Clean code
    • Modular
    • Coding style
    • Naming convension
  • Behavioural Questions
    • Handling team conflict
    • How to plan a project which has different

Java and Microservices

  • Java Microservice Interview Questions
  • Microservices vs monolithic architecture
  • How does security is implemented in Microservice Architecture?
  • When you will choose monolith over microservices? (In detail)
  • System Design Event Sourcing
  • Design a store stock update API for a highly loaded system.
  • Palindrome integer without string, or additional memory?
  • Write a function that takes positive integers A and B and returns the number bits set to 1 of the binary representation of A*B
  • Fix the implementation of a function that takes an array A of N integers representing the lengths of nails on a wooden board in non-decreasing order where integer K returns the maximal number of nails that can be positioned at matching length after hammering down at most K nails
  • Write a function that takes array A of N positive integers and positive integer K, returns the largest even sum of K elements or -1 if there are no such K elements.
  • What are generics in java?
  • How to make immutable a class?
  • What is docker and what is Kubernetes and how are they different
  • Postfix notation evaluation
  • Decorator Design Pattern
  • What are two types of dependency injection?
  • The task was to design a tic tac toe.
  • Reading data from files and aggregating/grouping and transforming
  • Maximum sum subsequence [dynamic programming]
  • Given a string of numbers reverse it and return an integer?
  • Given an array of nodes that represent a tree, find a subtree of the input nodes.
  • How to convert an Optional string to an integer without throwing an exception?
  • How to make post idempotent?
  • How do you implement security on messages passed from one microservice to another on a messaging system?
  • Create a singleton implementation?
  • How to have a synchronized counter?
  • What design patterns are you aware of and use frequently?
  • Are you familiar with Circuit breakers, retries design patterns?
  • How HashMap works internally in detail.
  • Do you know get function complexity of HashMap?
  • You are given a bunch of image names locations dates, sort based on date to generate a sequence number, but the output should be in the order in which the items were received.
  • You are given an array of integers to find the index which partitions the array into two with high numbers and low numbers. For example [5, -1, 3, 8,6] index 3 will partition the array to [5,-1,3] and [8,6] all the numbers in the second partition are greater than the first. The solution has to work in O(n).
  • String compression using character occurrence count ( “aaabb” => “a3b2” )
  • Path simplifier ( “/home/user1/..//user2/./dog/” => “/home/user2/dog”
  • Scala future conversion ( def convert(input: List[Future[Int]]): Future[List[Int]] = ??? )
  • Pascal’s Triangle
  • How the browser works?
  • What’s the difference between reflow and repaint?
  • Strings are immutable, comment, please.
  • How to write code that ensures Thread-safety.
  • Write code that finds if two strings have the same chars (including quantity).


  • What is Idempotency in rest API? How to implement?
  • What is a Rest API and what is the difference between out and patch
  • Write a Rest API?
  • Implement get and set in Rest APIs?
  • How to document Rest APIs?
  • What is REST API?
  • REST vs SOAP
  • Design a rest API?
  • How do you implement security in Rest APIs?


  • What is having in SQL?
  • Second largest salary from Employee table.
  • An SQL query using not in operator
  • When to use NoSQL database vs SQL (Relational) database?
  • How does scalability works in cases of NoSQL and relational SQL, what are the ACID properties of transactions?

Behavioral Questions at Zalando

  • In positions you found yourself as a tech lead, what do you feel are your strengths? What do you feel you owe to the success of the project? How did you impact or contribute to that?
  • Why do you want to work for us? how do you keep yourself updated?
  • What do you want to improve in yourself?
  • What role do you see yourself in the future?
  • How do you provide feedback to team members?
  • How do your team members rate you, biggest achievement, etc.?
  • What are your skills, experiences, working biography?
  • How do you prioritize speed and quality?
  • How do you resolve conflict between different teams?

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