Open Content Mathematics Curriculum

This is an evolving description of books and software that could be used to design a totally open undergraduate mathematics curriculum. This is meant to be a selective list, so you can consider these to be personal recommendations, not just links I've found promising. As such there will be a limited number of entries in each category. The first criteria in selecting texts is that preference will be given to those that are truly free - as in free to copy, free to modify, free to distribute, free to sell. For example, a text that prohibits commercial use does not have full freedom. Licensing terms are summarized for each item. The second criteria is that I have to have some reason to believe the text is accurate and has a selection of content that is in line with typical university courses.

First some comprehensive software, then lower-division (including introductory programming), concluding with upper-division (alphabetically by subject). Suggestions are encouraged, especially for empty categories or books you have used in a course, but inclusion is subject to the above discussion.