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Interview questions from top companies, mapped to the exact round they show up in. Prep for what you will actually face.

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Online AssessmentDSA / CodingMachine CodingLow-Level Design

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The Loop aggregates publicly shared interview experiences and curated commonly-asked questions, each labeled with its source. Not affiliated with any company listed.

CC BY-NC 4.0 · © 2026

← Klarna

Mid Backend at Klarna

BackendMidOutcome unknown◆ Commonly asked· 2025

Mid backend interview. Fundamentals mattered as much as getting to an answer.

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Pacific Atlantic water flow.
    MidMedium◆ Commonly asked
    #dfs#grid
    PracticeLeetCode↗GeeksforGeeks↗
  • Find minimum in rotated sorted array.
    MidMedium◆ Commonly asked
    #binary-search
    PracticeLeetCode↗GeeksforGeeks↗
  • Number of islands in a 2D grid.
    MidMedium◆ Commonly asked
    #bfs#dfs#grid
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Implement a token-bucket rate limiter as a service.
    MidMedium◆ Commonly asked
    #rate-limit
    PracticeGeeksforGeeks↗Search↗
  • Build auth middleware that verifies a JWT.
    MidMedium◆ Commonly asked
    #auth#security
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

Object-oriented / low-level design of a focused module.

  • Design a deck of cards + a card game.
    MidEasy◆ Commonly asked
    #oop
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • Difference between at-least-once and exactly-once delivery.
    MidHard◆ Commonly asked
    #messaging
    PracticeGeeksforGeeks↗Search↗
  • How does a bloom filter work and when would you use one?
    MidMedium◆ Commonly asked
    #data-structures#probabilistic
    PracticeGeeksforGeeks↗Search↗
  • How do you prevent and detect N+1 queries?
    MidMedium◆ Commonly asked
    #databases#orm
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

Values, collaboration, and past-experience (STAR) questions.

  • Tell me about a project you are most proud of.
    Mid◆ Commonly asked
    #star
  • How do you handle competing priorities from two managers?
    Mid◆ Commonly asked
    #prioritization#star

◆ This experience is composed from commonly reported questions for this role and level. Real, individually-shared interviews will be layered in over time.