CS50?s Introduction to Python

Harvard?s free course introducing programming using Python, with video lectures, notes, and problem sets.

LearnPython.org

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

King?s Wargaming Network

Academic network advancing theory and application of wargaming for research and teaching within Security Studies.

OpenStax Mathematics

Peer-reviewed, openly licensed textbooks covering college algebra, calculus, and statistics; downloadable for free in PDF or web format.

Why Machines Learn

Anil Ananthaswamy

A deep dive into the elegant mathematical principles behind machine learning

Stack Overflow - R Tag

A huge developer community answering detailed questions about R, packages, and applied statistics.

Paul?s Online Math Notes

Comprehensive lecture notes, examples, and problem sets on calculus, differential equations, algebra, and more, written in an accessible format.

Dataquest Free Data Analysis Courses

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

Programiz Python

Beginner-friendly tutorials covering Python basics, data structures, object-oriented programming, and standard libraries.

ETS GRE Official Prep

Free official materials from ETS including practice questions, POWERPREP online practice tests, and test-taker tips.

ModernDive: Statistical Inference via Data Science

Free online textbook teaching statistical inference and regression using R and tidyverse methods.

Saylor Academy - Mathematics

Free, full-length math courses (Linear Algebra, Abstract Algebra, Real Analysis, etc.) with exams and certificates.

PostgreSQL Tutorial

Free tutorials covering PostgreSQL features, SQL basics, stored procedures, and advanced database functions.

W3Schools SQL

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

Tableau Public Resources

Free resources and tutorials for using Tableau to create interactive visualizations and dashboards.

edX

edX is an American massive open online course provider created by Harvard and MIT. It hosts online university-level courses in a wide range of disciplines to a worldwide student body, including some courses at no charge.

Google Data Analytics Certificate (Audit Free)

Comprehensive beginner-to-intermediate program covering spreadsheets, SQL, R, visualization, and analytics workflows; free in audit mode.

Microsoft Learn - Data Analysis

Free learning paths covering data analysis basics and Power BI dashboards directly from Microsoft.

GregMat (YouTube)

Popular YouTube channel with hundreds of free GRE quant and verbal walkthroughs, strategies, and practice problem explanations.

W3Schools Python

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