If you're looking at this list you are probably a mathlet. You should know that unless the mathematics you're doing in the future is actually advanced, you will be better off using a pen and paper to do exercises than using a computer program.

Precalculus:

Lang, S. 1988 - Basic Mathematics, 1st Edition. Published by Springer Science + Business Media LLC.
Can be obtained at any good website for obtaining books for free.
Reviews: https://www.goodreads.com/en/book/show/79781.Basic_Mathematics

Basic Mathematics is a perfectly good book and is pretty easy. If you have cognitive issues and need colorful pictures however, William Marsh Rice University publishes the most popular remedial mathematics books in America under its OpenStax brand. If you feel they are better suited to you, this is the reading order:

Marecek, L., Anthony-Smith M., Mathis, A.H. 2020 - OpenStax Prealgebra, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/Prealgebra2e-WEB.pdf
Reviews: https://www.goodreads.com/book/show/36358239-prealgebra https://www.goodreads.com/book/show/34014382-prealgebra https://www.goodreads.com/book/show/55060608-prealgebra-2e-by-openstax https://www.goodreads.com/book/show/50264222-prealgebra-by-openstax https://www.goodreads.com/book/show/53761328-prealgebra

Marecek, L., Anthony-Smith M., Mathis, A.H. 2020 - Openstax Elementary Algebra, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/ElementaryAlgebra2e-WEB_EjIP4sI.pdf
Reviews: https://www.goodreads.com/book/show/36358259-elementary-algebra https://www.goodreads.com/book/show/58818958-elementary-algebra-2e-by-openstax https://www.goodreads.com/book/show/57698793-elementary-algebra-2e-by-openstax https://www.goodreads.com/book/show/56073031-elementary-algebra-2e-by-openstax https://www.goodreads.com/book/show/45883004-elementary-algebra-by-openstax

Abramson, J. and Falduto, V., Gross, R., Lippman, D., Rasmussen, M., Norwood, R., Belloit, N., Whipple, H., Magnier, J., Fernandez, C. 2021 - Openstax College Algebra, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/College-Algebra-2e-WEB.pdf
Reviews: https://www.goodreads.com/book/show/36477407-college-algebra https://www.goodreads.com/book/show/52415417-college-algebra-by-openstax https://www.goodreads.com/book/show/29083040-college-algebra

Marecek, L., Mathis, A.H. 2020 - Openstax Intermediate Algebra, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/IntermediateAlgebra2e-WEB.pdf
Reviews: https://www.goodreads.com/book/show/36358244-intermediate-algebra https://www.goodreads.com/book/show/55595058-intermediate-algebra-2e-by-openstax

Abramson, J. and Falduto, V., Gross, R., Lippman, D., Rasmussen, M., Norwood, R., Belloit, N., Whipple, H., Magnier, J., Fernandez, C. 2021 - Openstax Algebra and Trigonometry, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/Algebra-and-Trigonometry-2e-WEB.pdf
Reviews: https://www.goodreads.com/book/show/33653880-algebra-and-trigonometry https://www.goodreads.com/book/show/33653880-algebra-and-trigonometry

Abramson, J. and Falduto, V., Gross, R., Lippman, D., Rasmussen, M., Norwood, R., Belloit, N., Whipple, H., Magnier, J., Fernandez, C. 2021 - Openstax Precalculus, 2nd Edition. Published by William Marsh Rice University.
Can be obtained at https://assets.openstax.org/oscms-prodcms/media/documents/Precalculus_2e-WEB.pdf
Reviews: https://www.goodreads.com/book/show/36358233-precalculus https://www.goodreads.com/book/show/29953964-ccap-precalculus https://www.goodreads.com/book/show/34064528-precalculus https://www.goodreads.com/book/show/49941669-precalculus-by-openstax

Also:

Proofs:
-"Book of Proof", Hammack
-"How to Prove It", Velleman

Calculus:
-Stewart
-Spivak

Linear Algebra:
-"Linear Algebra Done Right"
-Shilov
-"A (Terse) Introduction to Linear Algebra"

Set Theory:
-"Naive Set Theory"

Geometry:
-"Foundations of Geometry", Borsuk

Abstract Algebra:
-"A Book of Abstract Algebra", Pinter
-Dummit & Foote
-"Algebra: Chapter 0"
-Artin
-Lang

Real Analysis:
-"Principles of Mathematical Analysis", Rudin
-"Understanding Analysis"
-"Counterexamples in Analysis"

Complex Analysis:
-Stein & Shakarchi
-Ahlfors
-"Introductory Complex Analysis", Silverman
-"Real and Complex Analysis", Rudin

Topology:
-Munkres
-"Counterexamples in Topology"

Number Theory:
-"A Classical Introduction to Modern Number Theory"
-"An Illustrated Theory of Numbers"
-"Computational Number Theory", Das

Galois Theory:
-Artin
-Rotman

Commutative Algebra:
-"Introduction to Commutative Algebra", Atiyah & Macdonald
-"Commutative Rings", Kaplansky

Algebraic Topology:
-Hatcher

Differential Geometry:
-"Differential Geometry of Curves and Surfaces", Do Carmo
-"Differential Geometry and Its Applications", Oprea

Elliptic Curves:
-"Arithmetic of Elliptic Curves", Silverman

Algebraic Geometry:
-"Ideals Varieties and Algorithms"
-"Algebraic Geometry: A Problem Solving Approach"
-"Basic Algebraic Geometry", Shafarevich

Harmonic Analysis:
-Stein & Murphy

Homological Algebra:
-Rotman

Algebraic Number Theory:
-Stewart & Tall
-"Primes of the form x2 + ny2"
-"Algebraic Theory of Numbers", Samuel
-"A Course in Arithmetic"
-Neukirch

Representation Theory:
-"Groups, Representations, and Characters", Hill

Category Theory:
-Awodey
-Mac Lane
-"An Invitation to Applied Category Theory"
-"Category Theory in Context"

Non-textbooks:

Fiction with mathematical themes:

.

Todo for v.2
Improve entries for books with incomplete entries
Include the booklists from /sqt/, /sqt/, the scienceandmathguide google site, the 4chan science and math wiki and various image macros