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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

← Jane Street

Senior Backend at Jane Street

BackendSeniorOutcome unknown◆ Commonly asked· 2023

A senior backend loop. Balanced across coding, design, and collaboration.

The loop · 6 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Longest substring without repeating characters.
    SeniorMedium◆ Commonly asked
    #sliding-window#string
    PracticeLeetCode↗GeeksforGeeks↗
  • Binary tree level order traversal.
    SeniorMedium◆ Commonly asked
    #tree#bfs
    PracticeLeetCode↗GeeksforGeeks↗
  • Combination sum.
    SeniorMedium◆ Commonly asked
    #backtracking
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Build a mini ORM query builder (select/where/join).
    SeniorHard◆ Commonly asked
    #parsing#sql
    PracticeGeeksforGeeks↗Search↗
  • Build a file-upload service with chunking and resume.
    SeniorHard◆ Commonly asked
    #streaming#storage
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 2 questions

System Design

High-level architecture of a large-scale system.

  • Design a rate-limited, multi-tenant public API gateway.
    SeniorHard◆ Commonly asked
    #gateway#rate-limit
    PracticeGeeksforGeeks↗Search↗
  • Design a file-sharing service with permissions.
    SeniorMedium◆ Commonly asked
    #storage#acl
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • Caching strategies: cache-aside, write-through, TTLs.
    SeniorMedium◆ Commonly asked
    #cache
    PracticeGeeksforGeeks↗Search↗
  • How does the OAuth 2.0 authorization-code flow work?
    SeniorMedium◆ Commonly asked
    #auth#security
    PracticeGeeksforGeeks↗Search↗
  • How do you secure secrets and handle auth tokens?
    SeniorMedium◆ Commonly asked
    #security
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 1 question

Hiring Manager

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

  • How do you give difficult feedback to a peer?
    Senior◆ Commonly asked
    #leadership
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
  • When did you have to make a decision with incomplete data?
    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.