Twitter / X

Real-time social platform with petabyte-scale data and ML ranking systems.

4 Rounds ~14 Days Hard

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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

All Roles Backend Engineer 35 Cloud Engineer 35 Data Engineer 35 Data Scientist 35 DevOps Engineer 35 Frontend Engineer 35 Full Stack Engineer 35 Machine Learning Engineer 35 Product Manager 35 Software Engineer 35

All Topics SQL 8 Machine Learning 7 Algorithms 5 Culture Fit 4 Experimentation 3 Product Sense 3 Statistics 2 Root Cause Analysis 1

Data Scientist • Behavioral • medium

Tell me about a time you had to ship a data science model or analysis under an extremely tight deadline. What corners did you cut?

#Execution #Prioritization #Bias for Action

Practice

Data Scientist • Behavioral • easy

Explain the concept of a p-value to a non-technical Product Manager who wants to launch a feature based on an A/B test.

#Statistics #Stakeholder Management

Practice

Data Scientist • Behavioral • medium

Describe a situation where you disagreed with a product manager or engineering lead on a key metric. How did you resolve it?

#Conflict Resolution #Data-Driven #Leadership

Practice

Data Scientist • Behavioral • medium

Tell me about a time your data analysis proved a widely held assumption within your company wrong.

#Analytical Thinking #Influence #Communication

Practice

Data Scientist • Behavioral • easy

X operates with a very lean team and fast-paced environment. How do you prioritize your tasks when everything is labeled 'high priority'?

#Time Management #Impact #Adaptability

Practice

Data Scientist • Behavioral • medium

Why do you want to work at X, and how do you handle rapid, unexpected changes in company direction or product strategy?

#Adaptability #Resilience #Motivation

Practice

Data Scientist • Coding • medium

Write a SQL query to calculate the 3-day rolling average of tweet impressions for each user over the past month.

#Window Functions #Aggregation #Time Series

Practice

Data Scientist • Coding • medium

Write a SQL query to find the top 3 creators by ad revenue payout in each geographic region for the last quarter.

#Ranking #Window Functions #Joins

Practice

Data Scientist • Coding • easy

Write a Python function to parse and extract all unique trending hashtags from a massive stream of tweet texts efficiently.

#Regex #Strings #Data Structures

Practice

Data Scientist • Coding • hard

Write a SQL query to calculate the Day 1 and Day 7 retention rates for users who recently subscribed to X Premium.

#Cohort Analysis #Self Joins #Date Functions

Practice

Data Scientist • Coding • easy

Write a SQL query to find users who liked a specific tweet but do not follow the author of that tweet.

#Joins #Filtering #Set Operations

Practice

Data Scientist • Coding • medium

Given a dataset of user sessions, write a Python script to merge overlapping session time intervals.

#Sorting #Intervals #Arrays

Practice

Data Scientist • Coding • hard

Write a SQL query to calculate the median time between a user's account creation and their first tweet.

#Percentiles #Date Math #CTEs

Practice

Data Scientist • Coding • easy

Write a Python function to calculate the cosine similarity between two sparse user-feature vectors.

#Math #Arrays #Linear Algebra

Practice

Data Scientist • Coding • medium

Write a SQL query to find the percentage of tweets that receive at least one reply within 5 minutes of being posted.

#Date/Time Functions #Joins #Aggregation

Practice

Data Scientist • Coding • medium

Given an array of daily tweet counts for a specific hashtag, write a Python function to find the longest contiguous streak of days where the count strictly increased.

#Arrays #Dynamic Programming

Practice

Data Scientist • Coding • hard

Write a SQL query to identify 'bot rings'—groups of 5 or more users who have retweeted the exact same set of 10 tweets within a 1-hour window.

#Complex Joins #Grouping #Anomaly Detection

Practice

Data Scientist • Coding • medium

Implement a basic TF-IDF algorithm from scratch in Python for a small corpus of tweets.

#NLP #Hash Maps #Math

Practice

Data Scientist • Coding • hard

Write a SQL query to calculate the 'viral coefficient' of a tweet (average number of new retweets generated by each retweet).

#Graph Data #Recursive CTEs #Aggregation

Practice

Data Scientist • System Design • hard

Design a recommendation system for the 'For You' timeline. How do you balance chronological relevance with algorithmic personalization?

#Recommender Systems #Ranking #Two-Tower Models

Practice

Data Scientist • System Design • hard

How would you build a machine learning model to detect spam or bot accounts in real-time as they register or tweet?

#Anomaly Detection #Streaming #Classification

Practice

Data Scientist • System Design • medium

How would you design a system to rank 'Trending Topics' in real-time?

#Ranking #Time Decay #NLP

Practice

Data Scientist • System Design • hard

Design a Graph ML system to power the 'Who to Follow' recommendations.

#Graph Neural Networks #Link Prediction #Scalability

Practice

Data Scientist • Technical • hard

How would you design an A/B test to evaluate the impact of the 'Community Notes' feature on the spread of misinformation?

#A/B Testing #Metrics Definition #Misinformation

Practice

Data Scientist • Technical • medium

We noticed a sudden 10% drop in Daily Active Users (DAU) on X. Walk me through how you would investigate the root cause.

#Debugging #Analytics #Product Sense

Practice

Data Scientist • Technical • hard

How do you handle network effects and interference when running an A/B test on a highly connected social graph like X?

#Network Effects #Graph Clustering #A/B Testing

Practice

Data Scientist • Technical • medium

What metrics would you define to measure the success of the X Premium (formerly Twitter Blue) subscription service?

#Monetization #KPIs #Strategy

Practice

Data Scientist • Technical • medium

How would you build an NLP model to classify and hide highly toxic replies in a tweet thread?

#NLP #Classification #Trust & Safety

Practice

Data Scientist • Technical • hard

If we introduce long-form tweets, how do you account for the novelty effect in your A/B test analysis?

#Statistical Significance #Novelty Effect #User Behavior

Practice

Data Scientist • Technical • medium

How would you predict user churn for X Premium subscribers? What features would be most important?

#Classification #Survival Analysis #Feature Engineering

Practice

Data Scientist • Technical • hard

How do you evaluate the trade-off between increasing ad load in the timeline and potential degradation of user engagement?

#Trade-offs #Monetization #Experimentation

Practice

Data Scientist • Technical • hard

When would you choose a Multi-Armed Bandit approach over traditional A/B testing for optimizing ad placements on X?

#Multi-Armed Bandit #Reinforcement Learning #Optimization

Practice

Data Scientist • Technical • medium

How would you deal with highly skewed data, such as user follower counts, when building a regression model?

#Data Transformation #Outliers #Modeling

Practice

Data Scientist • Technical • hard

How would you optimize the creator ad revenue sharing model to ensure fairness while maximizing overall platform content creation?

#Optimization #Allocation #Economics

Practice

Data Scientist • Technical • medium

If a user has a 10% chance of seeing an ad on any given page load, what is the probability they see at least one ad in 5 page loads?

#Probability #Binomial Distribution

Practice

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The "Standard" Interviewer

Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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Think Out Loud

Always explain your thought process before writing code or drawing architecture.

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