Free Online Calculus Text Books

In this list I have collected all useful and important free online calculus textbooks mostly in downloadable pdf format. Feel free to download and use these.

1. Elementary Calculus : An approach using infinitesimals by H. J. Keisler https://www.math.wisc.edu/~keisler/keislercalc-12-23-18.pdf
2. Multivariable Calculus by Jim Herod and George Cain http://people.math.gatech.edu/~cain/notes/calculus.html
3. Calculus by Gilbert Strang http://ocw.mit.edu/ans7870/textbooks/Strang/strangtext.htm
4. Calculus Bible by Neveln http://www.cs.widener.edu/~neveln/Calcbible.pdf
5. Lecture Notes for Applied Calculus by Karl Heinz Dovermann http://www.math.hawaii.edu/~heiner/calculus.pdf
6. A Summary of Calculus by Karl Heinz Dovermann http://www.math.hawaii.edu/~heiner/short.pdf
7. First Year Calculus Notes by Paul Garrett http://www.math.umn.edu/~garrett/calculus/
8. The Calculus of Functions of Several Variables by Professor Dan Sloughter https://tutorial.math.lamar.edu/classes/calciii/multivrblefcns.aspx
9. Difference Equations to Differential Equations : An Introduction to Calculus by Professor Dan Sloughter http://math.furman.edu/~dcs/courses/book/
10. Visual Calculus by Lawrence S. Husch http://archives.math.utk.edu/visual.calculus/
11. A Problem Text in Advanced Calculus by John Erdman http://web.pdx.edu/~erdman/PTAC/problemtext_pdf.pdf
12. Understanding Calculus by Faraz Hussain http://www.understandingcalculus.com/index.php
13. Advanced Calculus by Lynn Loomio and Schlomo Sternberg http://www.math.harvard.edu/~shlomo/docs/Advanced_Calculus.pdf
14. The Calculus Wikibook on Wikibooks http://upload.wikimedia.org/wikipedia/commons/a/a3/Calculus.pdf
15. Vector Calculus http://www.mecmath.net/calc3book.pdf
16. The Calculus for Engineers by John Perry http://books.google.com/books?id=FQE3AAAAMAAJ
17. Calculus Unlimited by J E Marsden & A Weinstein http://resolver.caltech.edu/CaltechBOOK:1981.001
18. Advanced Calculus by E B Wilson https://archive.org/details/ost-math-advanced_calculus
19. Differential and Integral Calculus by Daniel A Murray http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=math;cc=math;idno=00870001;view=image;seq=6;page=root;size=100
20. Elements of the Differential and Integral Calculus by W A Granville & P F Smith http://djm.cc/library/Elements_Differential_Integral_Calculus_Granville_edited_2.pdf
21. Calculus by Raja Almukkahal, Victor Cifarelli, Chun Tuk Fan & L Jarvis http://www.ck12.org/flexbook/flexbook/2878
22. A course on Pure Mathematics by G. H. Hardy http://archive.org/details/coursepuremath00hardrich
23. Calculus Volume I, II and III; and Student Guides by Marsden and Weinstein
    http://authors.library.caltech.edu/25030/
    http://authors.library.caltech.edu/25031/1/Calc1studentw.pdf
    http://authors.library.caltech.edu/25036/2/Calc2w.pdf
    http://authors.library.caltech.edu/25037/12/Calc2studentw.pdf
    http://authors.library.caltech.edu/25043/1/Calc3w.pdf
    http://authors.library.caltech.edu/25044/1/Calc3studentw.pdf
24. Calculus Early Transcendentals by David Guichard http://www.whitman.edu/mathematics/calculus/
25. Calculus in Context by Callahan, et.al. http://www.e-booksdirectory.com/details.php?ebook=8262
26. Introduction to Calculus Volume 1 and 2 by J.H. Heinbockel http://www.math.odu.edu/~jhh/Volume-1.PDF http://www.math.odu.edu/~jhh/Volume-2.PDF
27. Concepts in Calculus (1, 2 and 3) by Miklos Bona, Sergei Shabanov http://www.math.ufl.edu/~kees/Calc1final.pdf http://www.math.ufl.edu/~kees/Calc2final.pdf http://www.math.ufl.edu/~kees/Calc3final.pdf