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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.

MIT · © 2026

← Confluent

Senior Backend at Confluent

BackendSeniorRejected◆ Commonly asked· 2024

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

The loop · 6 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Longest substring without repeating characters.
    SeniorMedium◆ Commonly asked
    #sliding-window#string
    PracticeLeetCode↗GeeksforGeeks↗
  • Same tree.
    SeniorEasy◆ Commonly asked
    #tree
    PracticeLeetCode↗GeeksforGeeks↗
  • Sort colors.
    SeniorMedium◆ Commonly asked
    #two-pointers#array
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Design and build a URL-shortener service (API + storage).
    SeniorMedium◆ Commonly asked
    #api#hashing
    PracticeGeeksforGeeks↗Search↗
  • Build a background job runner with priorities.
    SeniorMedium◆ Commonly asked
    #queue#workers
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 2 questions

System Design

High-level architecture of a large-scale system.

  • Design a video streaming service like YouTube.
    SeniorHard◆ Commonly asked
    #cdn#storage#transcoding
    PracticeGeeksforGeeks↗Search↗
  • Design a pastebin with expiring links.
    SeniorMedium◆ Commonly asked
    #storage#ttl
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • How do you design a schema for a multi-currency ledger?
    SeniorHard◆ Commonly asked
    #databases#money
    PracticeGeeksforGeeks↗Search↗
  • How would you design and version a public REST API?
    SeniorMedium◆ Commonly asked
    #api-design
    PracticeGeeksforGeeks↗Search↗
  • Sharding vs partitioning vs replication.
    SeniorHard◆ Commonly asked
    #databases#scale
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 1 question

Hiring Manager

Scope, ownership, and role-fit discussion with the manager.

  • How do you balance tech debt against feature work?
    Senior◆ Commonly asked
    #prioritization
06

Round 06 · 2 questions

Behavioral / HR

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

  • Describe something you shipped that you were not proud of.
    Senior◆ Commonly asked
    #tradeoffs#star
  • How do you handle competing priorities from two managers?
    Senior◆ 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.