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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

← Algolia

Senior Backend at Algolia

BackendSeniorRejected◆ Commonly asked· 2023

6-round senior backend process. Coding-heavy early, design and behavioral later.

The loop · 6 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Course Schedule — detect a cycle / topological sort.
    SeniorMedium◆ Commonly asked
    #graph#topo-sort
    PracticeLeetCode↗GeeksforGeeks↗
  • Top K frequent elements.
    SeniorMedium◆ Commonly asked
    #heap#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
  • Kth smallest element in a BST.
    SeniorMedium◆ Commonly asked
    #tree#bst
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Implement a bulk-upsert endpoint with validation.
    SeniorMedium◆ Commonly asked
    #api#validation
    PracticeGeeksforGeeks↗Search↗
  • Implement an idempotent "charge" endpoint.
    SeniorHard◆ Commonly asked
    #idempotency#payments
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 2 questions

System Design

High-level architecture of a large-scale system.

  • Design a ticket booking system (inventory + concurrency).
    SeniorHard◆ Commonly asked
    #concurrency#transactions
    PracticeGeeksforGeeks↗Search↗
  • Design a search indexing pipeline (crawl to index to serve).
    SeniorHard◆ Commonly asked
    #indexing#pipeline
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • How do you prevent and detect N+1 queries?
    SeniorMedium◆ Commonly asked
    #databases#orm
    PracticeGeeksforGeeks↗Search↗
  • SQL vs NoSQL — how do you choose for a given workload?
    SeniorMedium◆ Commonly asked
    #databases
    PracticeGeeksforGeeks↗Search↗
  • Explain leader election and consensus (Raft) at a high level.
    SeniorHard◆ Commonly asked
    #distributed#consensus
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 1 question

Hiring Manager

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

  • Walk me through a technical trade-off you regret.
    Senior◆ Commonly asked
    #judgment
06

Round 06 · 2 questions

Behavioral / HR

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

  • Tell me about a time you disagreed and committed.
    Senior◆ Commonly asked
    #teamwork#star
  • Tell me about a project you are most proud of.
    Senior◆ Commonly asked
    #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.