Khan Academy
Free courses on math, science, history and more. Ideal for K-12 and lifelong learners.
edX
Massive open‑course platform from MIT & Harvard. Earn certificates or degrees, pay only if you want a verified credential.
FreeCodeCamp
Learn web development, data science, and algorithmic thinking through interactive coding challenges.
MIT OpenCourseWare
Access to thousands of MIT course materials—lecture notes, exams, and videos—for free.
Udemy
Huge catalog of professional courses on everything from AI to photography. Frequent sales drop prices to $10‑$20.
LibreTexts
Open‑ed curriculum covering life sciences, chemistry, physics, and engineering with peer‑reviewed content.
Stack Overflow Learning Paths
Curated learning tracks for programming languages and frameworks, with hands‑on projects and community support.