- Abstract Algebra Online - "This site contains many of the definitions and theorems from the area of mathematics generally called abstract algebra. It is intended for undergraduate students taking an abstract algebra class at the junior/senior level, as well as for students taking their first graduate algebra course."
- American Mathematical Society - Provides a useful guide to Math on the Web
- arXiv.org e-Print archive - Research paper archive, (formerly xxx.lanl.gov) for preprints and published papers in the fields of physics, mathematics, nonlinear sciences, and computer science.
- Ask Dr. Math - Homework questions for K-12 (and even college) answered by e-mail (Math Forum, Drexel)
- A Bibliography of Collected Works and Correspondence of Mathematicians - Steven W. Rockey, Mathematics Library, Cornell University
- Biographies of Women Mathematicians - Larry Riddle and students, Agnes Scott College, Atlanta, Georgia
- BUBL LINK - 510 Mathematics - Catalogue of selected Internet Resources
- Calculus on the Web - Gerardo Mendoza and Dan Reich, Temple University
- Canadian Mathematical Society (CAMEL)
- Comprehensive TeX Archive Network (CTAN) - Up-to-date TeX-related software.
- Documenta Mathematica - German (with English version)
- Educational Resources Information Center
- Einstein Online - Swiss Federal Institute of Technology, Zurich (in German). Includes a number of Einstein's letters and documents, primarily in German. There is a March 9, 1954 letter, in English, from Norman Thomas in which he declines an invitation to a conference and luncheon at the Nassau Tavern to be held in Einstein's honor because the arrangers of the celebration, the Emergency Civil Liberties Committee "have shown through the years anything but a consistent love of liberty."
- Eisenhower National Clearinghouse
- Electronic Library of Mathematics - Offered by the European Mathematical Society (EMS) in cooperation with FIZ Karlsruhe / Zentralblatt MATH.
- European Mathematical Information Service (EMIS)
- Frequently Asked Questions in Mathematics - Alex Lopez-Ortiz, University of Waterloo
- Glossary of Mathematical Mistakes - Paul Cox has gathered examples of "mathematical mistakes made over and over by advertisers, the media, reporters, politicians, activists, and in general many non-math people."
- Göttinger Digitalisierungszentrums - Digital Library at the Lower Saxony State and University Library, Göttingen, consists of over 1600 volumes and includes an Electronic Research Archive for Mathematics.
- Historical Math Monographs - Cornell Digital Library Document Browser provides access to the full-text, browsable by author and title.
- History of Mathematics - David R. Wilkins, Trinity College, Dublin. The text of Newton's Principia, Book Two, Lemma II, which has been described as the world's most important book, is available both in Latin and in an English translation.
- History of Mathematics Home Page - David E. Joyce, Department of Mathematics and Computer Science, Clark University
- How Many? A Dictionary of Units of Measurement - Created by Russ Rowlett, an education and mathematics professor at the University of North Carolina at Chapel Hill.
- Institute for Advanced Study School of Mathematics - Princeton, New Jersey.
- Integrator - "The power to do integrals as the world has never seen before."
- Institute of Mathematics - Russian Federation
- International Mathematical Union (IMU) - Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB), Germany
- MacTutor History of Mathematics Archives - Offers Biographies of over 1100 mathematicians, History Topics, Famous Curves Index and a Mathematician of the Day. Maintained by John J. O'Connor and Edmund F. Robertson of the School of Mathematical and Computational Sciences at the University of St. Andrews, Scotland.
- Martindale's Virtual Mathematics Center - Jim Martindale
- MathDL The MAA Mathematical Sciences Digital Library - Mathematical Association of America. Selected by Choice as an "Outstanding Academic Web Site of 2005"
- Math Forum - Drexel University School of Education web site for math educators (K-16).
- Math in Daily Life - How numbers affect everyday decisions: cooking, probability, banking, population, home decorating. With a collection of links to related resources.(An Annenberg Learner Online project.)
- MathSearch - "Search a collection of over 190,000 documents on English-language mathematics and statistics servers." Offered by Jim Richardson, School of Mathematics and Statistics, University of Sydney.
- Mathematical Quotations Server - Mark Woodard
- Math Archives - University of Tennessee, Knoxville. (Also known as the Math Archives.)
- Mathematics Genealogy Project - "Intent of this project is to compile information about ALL the mathematicians of the world." Project to list all individuals who have received a doctorate in mathematics. Users can search the database by personal name, school, or year of degree.
- Mathematics Museum - Japan
- Mathematics WWW Virtual Library - Florida State University
- Mathematics Web Sites Around the World - Penn State Mathematics Department.
- MathWorld
- MegaMathematics - Los Alamos National Laboratory project is "intended to bring unusual and important mathematical ideas to elementary school classrooms." Examples include Untangling the Mathematics of Knots and Welcome to the Hotel Infinity.
- MPRESS: Mathematics Preprint Search System - Part of the European Mathematical Information Service, offered by the European Mathematical Society
- National Council of Teachers of Mathematics
- On-Line Encyclopedia of Integer Sequences - Neil J. A. Sloane, Technology Consultant, AT&T Labs-Research
- PBS TeacherSource: Math - Recommended books and websites, information on grants and conferences, and a searchable video database which will locate video clips and lesson plans on different mathematical topics and teaching techniques for grades K-12.
- Past Notable Women of Mathematics - Elisabeth Freeman & Susanne Hupfer, Ada Project, Yale University.
- Prime Page - Chris K. Caldwell's site, "the prime source for information about prime numbers," also includes Largest Known Primes
- PRIME Mathematics Encyclopedia - "Math Academy Online Platonic Realms web site was initiated by a small group of math and math education graduate students, led by B. Sidney Smith, the current owner and editor-in-chief, at the University of Colorado at Boulder in 1997."
- Project Euclid
- "User-centered initiative to create an environment for the effective and affordable distribution of serial literature in mathematics and statistics."
- R. Buckminster Fuller's Synergetics (c1997) - Multi-disciplinary work, subtitled "Explorations in the Geometry of Thinking" was first published by Macmillan in two volumes in 1975 and 1979. This digital edition, with annotations and commentary, is a collaborative effort of E. J. Applewhite and Robert Gray.
- Roman Numerals and Dates - Paul Lewis. Compare to Lee's Useless Decimal to Roman Numeral Converter.
- TeX Users Group - Organization for those who have an interest in systems for text typesetting and font design, for use in typesetting; in particular, for typesetting math and other technical material.
- WIMS: Interactive Mathematics on the Internet - Interactive exercises, graphical mathematical games, online math tools. (Xiao Gang, University of Nice)
- Women in Math Project - Extensive collection of biographies on women mathematicians, as well as bibliographies, statistics, information on associations and conferences and links to other resources. Project directed by Marie Vitulli, Department of Mathematics, University of Oregon.