theloop
CompaniesRoundsQuestionsSearchProgress
theloop

Interview questions from top companies, mapped to the exact round they show up in. Prep for what you will actually face.

View source

Browse

CompaniesSearchAll rounds

Rounds

Online AssessmentDSA / CodingMachine CodingLow-Level Design

Contribute

Share an interviewReport an issueStar on GitHub

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

← Plaid

Mid Backend at Plaid

BackendMidRejected◆ Commonly asked· 2024

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.

  • Contains duplicate.
    MidEasy◆ Commonly asked
    #array#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
  • Invert a binary tree.
    MidEasy◆ Commonly asked
    #tree
    PracticeLeetCode↗GeeksforGeeks↗
  • Product of array except self.
    MidMedium◆ Commonly asked
    #array#prefix-sum
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Build a key-value store with TTL expiry.
    MidMedium◆ Commonly asked
    #cache#ttl
    PracticeGeeksforGeeks↗Search↗
  • Build an in-memory pub/sub with topic subscriptions.
    MidMedium◆ Commonly asked
    #pub-sub
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

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

  • Design a splitwise-style expense sharer.
    MidMedium◆ Commonly asked
    #oop#graph
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • How does the OAuth 2.0 authorization-code flow work?
    MidMedium◆ Commonly asked
    #auth#security
    PracticeGeeksforGeeks↗Search↗
  • How do circuit breakers and bulkheads improve resilience?
    MidMedium◆ Commonly asked
    #reliability
    PracticeGeeksforGeeks↗Search↗
  • Explain optimistic vs pessimistic locking.
    MidHard◆ Commonly asked
    #databases
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

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

  • Tell me about a time you failed and what you learned.
    Mid◆ Commonly asked
    #growth#star
  • How do you handle being blocked for several days?
    Mid◆ Commonly asked
    #ownership#star

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