Whatnot Interview Questions

Whatnot Interview Questions

Practice 25 real interview questions from Whatnot. Covers Coding & Algorithms, System Design, Analytics & Experimentation, Data Manipulation (SQL/Python). For roles including Software Engineer, Data Scientist, Machine Learning Engineer.

25 Questions 1 Company07.14.2026
Showing 20 results
Role
Whatnot logo
Whatnot
Medium
Software Engineer Locked

Design a Direct Messaging System for an E-commerce Marketplace

This question evaluates a candidate's ability to design a real-time messaging system, covering distributed systems concepts like durability, ordering ...

System Design
9
0
96 people solved
Jun 11, 2026
Whatnot logo
Whatnot
Medium
Software Engineer Locked

Design a Charity Donation Website

This question evaluates system architecture and reliability engineering skills, focusing on payment integration, asynchronous processing, idempotency,...

System Design
22
0
177 people solved
May 30, 2026
Whatnot logo
Whatnot
Medium
Data Scientist Locked

Explain Your Product Motivation and Transferable Experience

Prepare a concise explanation of your product motivation and the experience you would transfer into a data-science role. This behavioral interview que...

Behavioral & Leadership
3
0
23 people solved
May 23, 2026
Whatnot logo
Whatnot
Medium
Data Scientist Locked

Debug a Python Aggregation Loop with Dictionaries and Lists

Review a Python aggregation routine that uses dictionaries, lists, and loops, then explain how you would make it correct and robust. This interview ex...

Software Engineering Fundamentals
5
0
39 people solved
May 23, 2026
Whatnot logo
Whatnot
Medium
Software Engineer

Design A WhatsApp-Style Messaging System

Design a messaging system similar to WhatsApp. Users should send one-to-one and group messages, receive messages in near real time, and recover messag...

System Design
4
0
35 people solved
May 8, 2026
Whatnot logo
Whatnot
Easy
Software Engineer

Design an Online Coding Judge

Design a large-scale online coding practice and contest platform. Users should be able to browse programming problems, submit code in multiple languag...

System Design
5
0
65 people solved
Apr 24, 2026
Whatnot logo
Whatnot
Medium
Software Engineer Locked

Design an Online Coding Contest Platform

This question evaluates a candidate's ability to design a scalable, secure System Design for an online coding contest platform with emphasis on safely...

System Design
8
0
91 people solved
Apr 7, 2026
Whatnot logo
Whatnot
Medium
Software Engineer Locked

Content Safety Filter

This coding question tests string parsing, tokenization logic, and pattern-matching algorithm design in a practical content moderation context. It eva...

Coding & Algorithms
1
0
12 people solved
Jun 24, 2026
Whatnot logo
Whatnot
Medium
Data ScientistSenior+

Define Marketplace Success Metrics and Investigate Their Movement

Define Marketplace Success Metrics and Investigate Their Movement A two-sided live-commerce marketplace asks you to define success metrics. A primary ...

Analytics & Experimentation
0
0
7 people solved
Mar 30, 2026
Whatnot logo
Whatnot
Medium
Software Engineer

Propose and Validate a Mobile App Improvement

Assume you are working on a consumer mobile app. Propose one product improvement that could improve user engagement, retention, or conversion. Your an...

System Design
6
0
58 people solved
Jan 24, 2026
Whatnot logo
Whatnot
Medium
Data Scientist Locked

Measure a Discovery Boost in a Two-Sided Marketplace

Design a measurement plan for a discovery change in a two-sided marketplace. The interview question evaluates metric selection, experiment design, int...

Analytics & Experimentation
1
0
17 people solved
May 23, 2026
Whatnot logo
Whatnot
Medium
Machine Learning Engineer

Improve and debug the shopping app

You are evaluating a live-shopping mobile app from a product-minded engineering perspective. Answer the following as one integrated exercise: 1. What ...

System Design
13
0
157 people solved
Jan 17, 2026
Whatnot logo
Whatnot
Medium
Data Scientist Locked

Turn a Marketplace Data Insight into an Actionable Product Plan

Practice turning a marketplace data observation into an interview-ready product and analytics plan. The question tests problem framing, stakeholder al...

Analytics & Experimentation
1
0
13 people solved
May 23, 2026
Whatnot logo
Whatnot
Medium
Data ScientistSenior+

Calculate Monthly Customer Retention

Calculate Monthly Customer Retention Write one PostgreSQL SELECT statement or CTE query. Do not create, alter, or modify tables. Schema orders | colum...

Data Manipulation (SQL/Python)
0
0
3 people solved
Mar 30, 2026
Whatnot logo
Whatnot
Medium
Data ScientistSenior+

Compute a Seven-Day Rolling Average

Compute a Seven-Day Rolling Average Write one PostgreSQL SELECT statement or CTE query. Do not create, alter, or modify tables. Schema daily_metrics |...

Data Manipulation (SQL/Python)
0
0
2 people solved
Mar 30, 2026
Whatnot logo
Whatnot
Medium
Software Engineer

Synchronize Shared Data Across Two Lists

Build a small mobile app with two list screens that fetch and display data. Some items may appear in both lists. Each item has at least: - id - title ...

Software Engineering Fundamentals
5
0
55 people solved
Jan 24, 2026
Whatnot logo
Whatnot
Medium
Machine Learning Engineer

Design trending livestream discovery

Design a system for a live-commerce platform that surfaces trending livestreams to users. Assume an ML model for scoring trendiness or relevance alrea...

ML System Design
7
0
117 people solved
Jan 17, 2026
Whatnot logo
Whatnot
Easy
Software Engineer

Solve Adjacent-Deletion and Sorted-Square Problems

Solve the following coding problems. Discuss the approach and complexity before implementation. Problem 1: Remove adjacent duplicate pairs Given a str...

Coding & Algorithms
0
0
14 people solved
Apr 24, 2026
Whatnot logo
Whatnot
Hard
Software Engineer

Merge Two Sorted Arrays

Merge Two Sorted Arrays Given two integer arrays sorted in nondecreasing order, return a new array containing every value from both inputs in nondecre...

Coding & Algorithms
1
0
12 people solved
Jul 14, 2026
Whatnot logo
Whatnot
Hard
Software Engineer

Remove All Adjacent Duplicate Pairs

Remove All Adjacent Duplicate Pairs Given a string s, repeatedly remove pairs of equal adjacent characters. A removal can make a new equal pair adjace...

Coding & Algorithms
1
0
12 people solved
Jul 14, 2026

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Whatnot Interview Questions (Updated 2026) | PracHub