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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

← Dropbox

Senior Backend at Dropbox

BackendSeniorOffer◆ Commonly asked· 2025

6-round senior backend process. 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.

  • 3Sum.
    SeniorMedium◆ Commonly asked
    #two-pointers#array
    PracticeLeetCode↗GeeksforGeeks↗
  • Implement a trie (prefix tree).
    SeniorMedium◆ Commonly asked
    #trie
    PracticeLeetCode↗GeeksforGeeks↗
  • Longest increasing subsequence.
    SeniorHard◆ Commonly asked
    #dp#binary-search
    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↗
  • Build a webhook receiver with signature verification.
    SeniorMedium◆ Commonly asked
    #security#api
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 2 questions

System Design

High-level architecture of a large-scale system.

  • Design a typeahead / autocomplete service.
    SeniorHard◆ Commonly asked
    #trie#cache#ranking
    PracticeGeeksforGeeks↗Search↗
  • Design a ride-matching backend (riders ↔ nearby drivers).
    SeniorHard◆ Commonly asked
    #geospatial#matching#realtime
    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↗
  • How does the OAuth 2.0 authorization-code flow work?
    SeniorMedium◆ Commonly asked
    #auth#security
    PracticeGeeksforGeeks↗Search↗
  • ACID vs BASE and transaction isolation levels.
    SeniorHard◆ Commonly asked
    #databases#transactions
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 1 question

Hiring Manager

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

  • Tell me about a technical bet that did not pay off.
    Senior◆ Commonly asked
    #risk#judgment
06

Round 06 · 2 questions

Behavioral / HR

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

  • Tell me about a time you led without a title.
    Senior◆ Commonly asked
    #leadership#star
  • Tell me about a time you simplified something overly complex.
    Senior◆ Commonly asked
    #judgment#star

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