Science

Astronomy

Astronomy by OpenStax

Biology

Concepts of Biology by OpenStax Biology by OpenStax

Microbiology

Microbiology by OpenStax

Anatomy and Physiology

Anatomy and Physiology by OpenStax

Chemistry

Chemistry by OpenStax Chemistry: Atoms First by OpenStax

Mathematics

Category Theory

Category Theory for Programmers by Bartosz Milewski

[Book] An Invitation to Applied Category Theory: Seven Sketches in Compositionality by Brendan Fong and David I. Spivak [Drive]

Philosophy

Stanford Encyclopedia of Philosophy

Physics

University Physics, Volume 1 by OpenStax (mechanics, sound, oscillations, and waves) University Physics, Volume 2 by OpenStax (thermodynamics, electricity and magnetism) University Physics, Volume 3 by OpenStax (optics and modern physics)

The Feynman Lectures on Physics, Volume 1 by Richard P. Feynman (mainly mechanics, radiation, and heat) The Feynman Lectures on Physics, Volume 1 by Richard P. Feynman (mainly electromagnetism and matter) The Feynman Lectures on Physics, Volume 1 by Richard P. Feynman (mainly quantum mechanics)

Electrodynamics

[Book] Introduction to Electrodynamics by David J. Griffiths [Drive]

Quantum mechanics

[Book] Introduction to Quantum mechanics by David J. Griffiths [Drive]

Psychology

Psychology by OpenStax