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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

← SpaceX

Mid Backend at SpaceX

BackendMidOutcome unknown◆ Commonly asked· 2025

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

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Word ladder — shortest transformation sequence.
    MidHard◆ Commonly asked
    #bfs#graph
    PracticeLeetCode↗GeeksforGeeks↗
  • Maximum subarray (Kadane).
    MidMedium◆ Commonly asked
    #array#dp
    PracticeLeetCode↗GeeksforGeeks↗
  • Sort colors.
    MidMedium◆ Commonly asked
    #two-pointers#array
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Build an in-memory rate limiter as a middleware.
    MidMedium◆ Commonly asked
    #rate-limit#middleware
    PracticeGeeksforGeeks↗Search↗
  • Build a REST endpoint with pagination, filtering and sorting.
    MidMedium◆ Commonly asked
    #api#pagination
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

Object-oriented / low-level design of a focused module.

  • Design a hotel-reservation system core.
    MidMedium◆ Commonly asked
    #oop#concurrency
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • What is a deadlock and how do you avoid one?
    MidHard◆ Commonly asked
    #concurrency
    PracticeGeeksforGeeks↗Search↗
  • How do you run a zero-downtime database migration?
    MidHard◆ Commonly asked
    #databases
    PracticeGeeksforGeeks↗Search↗
  • ACID vs BASE and transaction isolation levels.
    MidHard◆ Commonly asked
    #databases#transactions
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

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

  • Describe working with an ambiguous or shifting requirement.
    Mid◆ Commonly asked
    #ambiguity#star
  • Describe mentoring or unblocking another engineer.
    Mid◆ Commonly asked
    #mentorship#star

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