I found these two machine/deep learning books online straight from the authors for free it seems:
New general deep learning overview from Simon J.D Prince
https://udlbook.github.io/udlbook/
More old school sciencey with statistics angle:
https://www.statlearning.com/
Let me know if there are more quality texts online. There are so many books out now I feel it’s not feasible to buy them all.