These textbooks either have an HTML version (with accessible math) or LaTeX sources available.
Computer Science
- A Data-Centric Introduction to Computing
- An Introduction to Computer Networks
- Algorithmica
- Beej’s Guides: network programming and unix interprocess coomunication
- Build Your Own Redis with C/C++
- Computer Networks: A Systems Approach
- Computer Organization E-Book By Stephen Marz
- Computer Science from the Bottom Up
- Crafting Interpretors
- Digital Superpowers
- Dive Into Systems
- High Performance Browser Networking by ILYA GRIGORIK
- Hypermedia Systems
- How To Design Programs 2E
- Information Theory, Inference and Learning Algorithms by David MacKay
- Introduction to Information Retrieval
- Invariants: A Generative Approach to Programming
- Linux from scratch: build your own Linux distro!
- OCaml Programming: Correct + Efficient + Beautiful
- Open Data Structures
- Problem Solving with Algorithms and Data Structures using Python
- School of SRE
- Theory of Computation by Jim Hefferon
- The Secret World of Data Structures and Algorithms
- Use The Index, Luke
- Great (and Free!) Web Development Books You Can Get Online
Audio Digital Signal Processing
- Introduction To Digital Filters With Audio Applications by JULIUS O. SMITH III
- Introduction to Speech Processing
- Physical Audio Signal Processing For Virtual Musical Instruments And Audio Effects by JULIUS O. SMITH III]
Game Development
Math
Calculus
Introduction To Proofs
Linear Algebra
Probability And Statistics
- Introduction to Probability, Statistics, and Random Processes by Hossein Pishro-Nik
- The BOOKDOWN home page has some featured books on statistics, datra science and R.