Swirl: Learn R in R

An interactive R package that teaches R programming and data science concepts directly inside the R console.

Princeton Review GRE Practice

Free practice test access, strategy sessions, and sample GRE questions.

MiT Open CourseWare

MIT OpenCourseWare offers free access to thousands of MIT course materials?lectures, assignments, and exams?covering subjects from engineering and computer science to economics and the humanities. It's open learning at its best, with no registration required.

Kaggle Learn R

Hands-on mini-courses for R programming, data visualization, and machine learning with interactive notebooks in the browser.

SQLZoo

Hands-on SQL practice with guided problems, quizzes, and interactive database queries to reinforce concepts.

LearnPython.org

Interactive, browser-based Python tutorials ranging from basic syntax to advanced modules.

W3Schools SQL

Beginner-friendly SQL tutorials with examples of queries, joins, constraints, and subqueries, plus an interactive editor.

Art of Problem Solving (AoPS) Online Resources

Challenging problems, explanations, and articles designed for advanced high school and college-level students interested in problem solving and Olympiad-style math.

Kaggle Learn - Data Analysis

Hands-on mini-courses for Python, R, SQL, and visualization with Jupyter notebooks that run directly in the browser.

DataCamp

DataCamp is an online learning platform that specializes in data science, analytics, and artificial intelligence, offering interactive courses in Python, SQL, R, and other key technologies. Learners can build practical skills through hands-on coding exercises, real-world projects, and guided career tracks?all accessible from a browser at their own pace.

Manhattan Review Free GRE Resources

Free practice problems, diagnostic tests, and study tips from test prep experts.

EDX ? Analyzing and Visualizing Data with Power BI (Audit Free)

University of Illinois & Microsoft course teaching Power BI for analytics and reporting, free in audit mode.

Dataquest Free Data Analysis Courses

Browser-based lessons in Python, SQL, and data visualization; first modules free.

W3Schools Python

Step-by-step interactive lessons for Python basics, data structures, and functions, with hands-on coding snippets.

Designing Machine Learning Systems

Chip Huyen

A practical blueprint for building production-ready ML systems with scalability and reliability

Microsoft Learn ? Power BI

Official Microsoft Learn platform with guided, hands-on modules for Power BI, covering everything from basics to advanced analytics.

Nexus: A Brief History of Information Networks

Brian Christian

A sweeping narrative on the evolution and impact of global information networks

PyBites Platform (Free Exercises)

Short, practical coding exercises (some free) focused on solving real-world problems in Python.

SQLBI

Extensive library of free articles, guides, and videos on DAX, data modeling, and BI concepts by expert consultants Alberto Ferrari and Marco Russo.

RADACAD Power BI Blog

Practical tutorials and tips on Power BI modeling, DAX, Power Query, and real-world scenarios written by MVPs.