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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

← Jar

Senior Backend at Jar

BackendSeniorOffer◆ Commonly asked· 2025

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

The loop · 6 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Rotate array.
    SeniorMedium◆ Commonly asked
    #array
    PracticeLeetCode↗GeeksforGeeks↗
  • Reverse nodes in k-group.
    SeniorHard◆ Commonly asked
    #linked-list
    PracticeLeetCode↗GeeksforGeeks↗
  • Same tree.
    SeniorEasy◆ Commonly asked
    #tree
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Implement a job queue with retries and backoff.
    SeniorHard◆ Commonly asked
    #queue#reliability
    PracticeGeeksforGeeks↗Search↗
  • Design and build a URL-shortener service (API + storage).
    SeniorMedium◆ Commonly asked
    #api#hashing
    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 payment processing + idempotency system.
    SeniorHard◆ Commonly asked
    #idempotency#consistency
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • What is backpressure and how do you handle it?
    SeniorHard◆ Commonly asked
    #streaming#reliability
    PracticeGeeksforGeeks↗Search↗
  • How do you secure secrets and handle auth tokens?
    SeniorMedium◆ Commonly asked
    #security
    PracticeGeeksforGeeks↗Search↗
  • Explain database replication lag and how to mitigate it.
    SeniorMedium◆ Commonly asked
    #databases#replication
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 1 question

Hiring Manager

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

  • How do you scope and staff a multi-month project?
    Senior◆ Commonly asked
    #planning#leadership
06

Round 06 · 2 questions

Behavioral / HR

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

  • A time you made a mistake in production — what happened next?
    Senior◆ Commonly asked
    #ownership#star
  • Tell me about the most impactful project of your career.
    Senior◆ Commonly asked
    #impact#star

Practice each round across every company

  • DSA / Coding
  • Machine Coding
  • System Design
  • Tech Deep-Dive
  • Hiring Manager
  • 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.