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Practice real interview questions for Data Science, Machine Learning, and AI Engineering roles. Simulate interviews with AI and build portfolio projects — everything you need to walk into your next interview with confidence.
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Everything You Need to Succeed
From practice questions to portfolio projects — for Data Science, Machine Learning, and AI Engineering interviews.
Interview Questions
1000+ real coding and concept questions for Data Science, ML, and AI Engineering interviews. SQL, Python, ML system design, statistics, and more.
Mock Interviews
AI-powered mock interviews for Data Scientist, ML Engineer, and AI Engineer roles — timed sessions with detailed feedback on code and communication.
Data Labs
Real take-home projects — including ML and AI engineering assignments — powered by our cloud hosted Python notebooks. No setup required.
Learning Paths
Free comprehensive SQL and Python paths — the foundations every data and AI interview builds on. 6 modules, 36 lessons, and 160+ questions each.
Performance Insights
Track your skills, benchmark against the community, and build your public data profile.
AI StrataTools
Validate and optimize your code in real environments — for Python, SQL, and applied ML workflows.
Built for the AI Engineering Interview Loop
Machine Learning Engineer and AI Engineer interviews go beyond SQL and Leetcode-style questions. Filter every question, project, and mock interview by the role you are targeting — AI Engineer, Machine Learning Engineer, Applied Scientist, MLOps Engineer, and more.
ML System Design & Modeling
350+ concept questions filtered to AI and ML roles — system design, modeling, statistics, and probability. Submit an answer and the AI Evaluator scores it on completeness, accuracy, depth, and structure.
Practice AI Engineer concept questionsTake-home roundML Take-Home Projects
60+ real take-home assignments tagged for AI and ML roles, in cloud-hosted Python notebooks. No local setup — build the project and share it straight from your Performance page.
Browse ML take-home projectsInterview roundRole-Targeted Mock Interviews
Run a timed mock interview for the exact role you are targeting — AI Engineer, Machine Learning Engineer, or Data Scientist — with detailed feedback on your code and communication.
Start an AI Engineer mock interviewPractice Questions from Top Companies
Master the exact questions asked at Google, Meta, Amazon, and 200+ other companies — for Data Scientist, ML Engineer, and AI Engineer roles. From coding challenges to ML system design, we've got you covered.
Interview Coding Questions
1000+ real coding challenges
Practice SQL and Python coding questions with our interactive code editor. Write, run, and validate your solutions in real-time.
SQL Dialects
Python Libraries
Other Languages
Interview Concepts
Master non-coding interview rounds
Prepare for the full interview process with conceptual questions that test your analytical thinking, business acumen, and technical knowledge — including the ML system design and modeling rounds that decide AI and ML Engineer offers.
Question Types
Submit your answer and get detailed AI feedback — scored on completeness, accuracy, depth, structure, and practical relevance, with specific improvement suggestions.
Simulate Real Interviews Before the Real Thing
Practice under real conditions with an AI interviewer that tracks your time and delivers detailed feedback on both your code and communication — for Data Scientist, ML Engineer, and AI Engineer interview loops.
Online Assessment
60 min · 2 Qs
Phone Interview
90 min · 2 Qs
Onsite Interview
120 min · 3 Qs
- Choose your role, company, and difficulty — or Quick Start instantly
- Detailed scoring on code quality, correctness, and communication
- Personalized AI review with actionable feedback on your code and reasoning
Mock Interview Session
Data Analyst · Google · Medium
SMS Confirmations by FB
Find the number of phone numbers that were sent a confirmation SMS text by carrier on August 7, 2020…
Table Schema
- carrierTEXT
- countryTEXT
- dsDATE
- phone_numberBIGINT
- typeTEXT
Build Real Data & AI Projects in Our Cloud Hosted Notebooks
Practice real take-home assignments from top companies — including ML and AI engineering assignments. Build your portfolio and share it directly from your Performance page — no local setup required.
- Real take-home assignments from top tech companies, including ML and AI roles
- Cloud-hosted Python notebooks — no installation needed
- Build and showcase your data portfolio for interviews
- Share your work publicly from your Performance page
Structured Learning Paths for SQL & Python
Go from foundations to interview-ready with our comprehensive free learning paths — the same foundations that underpin Data Science, ML, and AI Engineering interviews. Lessons, practice questions, and hands-on projects included.
- Comprehensive SQL: foundations to window functions
- Comprehensive Python: pandas, data wrangling, and interview patterns
- 36 lessons and 160+ practice questions per path
- Completely free — no premium required
Comprehensive SQL
Master SQL from foundations to advanced window functions. 6 modules covering everything you need for data analyst interviews.
- 1
SQL Foundations
8 lessons · 4 hr 30 min
- 2
Aggregating & Grouping Data
6 lessons · 3 hr 25 min
- 3
Working with Multiple Tables
8 lessons · 4 hr 5 min
- 4
Subqueries & CTEs
4 lessons · 2 hr 20 min
- 5
Date, Time & Text Functions
5 lessons · 3 hr 20 min
- 6
Window Functions
5 lessons · 2 hr 55 min
AI StrataTools run your code — so you don't run into errors
Validate and optimize your Python and SQL by running it in real environments, delivering reliable results and reducing AI hallucinations — for both data and applied ML workflows.
Transformed Code:
SELECT
customer_id,
order_date,
ROW_NUMBER() OVER (
PARTITION BY customer_id
ORDER BY order_date DESC
) AS rn
FROM orders;Loved by Data & AI Professionals
Join thousands who landed jobs as Data Scientists, ML Engineers, and AI Engineers at top tech companies
“StrataScratch has been super helpful. I started with barely being able to finish an easy SQL query to no problem solving most of the medium level in just a few days.”
Kyle
Twitch
“StrataScratch is hands down the best platform if you are preparing for or am working as a data analyst/scientist/engineer. Happy to share that I have gotten an offer from Amazon as a Data Analyst.”
Triman
Amazon
“I really wanted to get into data analytics and data science but never really understood the importance of SQL. The questions are really very realistic and I was asked similar questions in my coding rounds.”
Hemant R
Credit Karma
“SQL is something that is super important and plays a key role in Data Analysis. I used to practice 2-3 SQL problems everyday. The discussion forum and solution with clear understanding cleared my barriers.”
Vikram
Microsoft
“StrataScratch and the community really helped me prep for the interview — I ended up getting the Data Scientist internship!”
Joe
Microsoft
“StrataScratch is awesome! It's the first place I found that allows you to use python in addition to SQL. The Facebook questions were quite similar to the ones that I saw in my interview today.”
Ryan
Level Up Your Data Skills
From SQL fundamentals to AI-era interview prep — free guides, tutorials, and resources from our team
How SQL EXISTS Works and When to Use It
Ignore EXISTS at your own peril! Learn how SQL EXISTS actually works, how it compares to IN and JOIN, and solve actual interview questions.
Tihomir Babic -
SQL Execution Order Explained With Real Query Examples
SQL execution order decides how queries actually run. Learn why FROM comes first, how aliases fail in WHERE, and when to use HAVING, with real examples.
Sara Nobrega -
Your Next Data or AI Interview Is Closer Than You Think
Start practicing real Data Science, ML, and AI Engineering interview questions today. No credit card required.