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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

← Mercury

New Grad / Junior Backend at Mercury

BackendNew Grad / JuniorRejected◆ Commonly asked· 2024

A junior backend loop. Pragmatic questions — more real-world than pure puzzles.

The loop · 5 rounds

01

Round 01 · 1 question

Online Assessment

Timed online coding / aptitude screen, usually the first filter.

  • Simulate a simplified card game and score it.
    New Grad / JuniorMedium◆ Commonly asked
    #simulation
    PracticeGeeksforGeeks↗Search↗
02

Round 02 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Merge k sorted lists.
    New Grad / JuniorHard◆ Commonly asked
    #heap#linked-list
    PracticeLeetCode↗GeeksforGeeks↗
  • Maximum subarray (Kadane).
    New Grad / JuniorMedium◆ Commonly asked
    #array#dp
    PracticeLeetCode↗GeeksforGeeks↗
  • Top K frequent elements.
    New Grad / JuniorMedium◆ Commonly asked
    #heap#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
03

Round 03 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Implement a leaderboard API backed by a sorted set.
    New Grad / JuniorMedium◆ Commonly asked
    #redis#ranking
    PracticeGeeksforGeeks↗Search↗
  • Implement a job queue with retries and backoff.
    New Grad / JuniorHard◆ Commonly asked
    #queue#reliability
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • Explain JWT structure and common pitfalls.
    New Grad / JuniorMedium◆ Commonly asked
    #auth#security
    PracticeGeeksforGeeks↗Search↗
  • ACID vs BASE and transaction isolation levels.
    New Grad / JuniorHard◆ Commonly asked
    #databases#transactions
    PracticeGeeksforGeeks↗Search↗
  • Explain connection pooling and why it matters.
    New Grad / JuniorMedium◆ Commonly asked
    #databases
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

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

  • Describe a conflict with your manager and the outcome.
    New Grad / Junior◆ Commonly asked
    #conflict#star
  • Tell me about the most impactful project of your career.
    New Grad / Junior◆ Commonly asked
    #impact#star

Practice each round across every company

  • Online Assessment
  • DSA / Coding
  • Machine Coding
  • Tech Deep-Dive
  • Behavioral / HR

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