The Best Websites for Learning Mathematics in 2026

Why This Guide Exists

The internet has transformed how we learn mathematics. There are now hundreds of websites offering lectures, exercises, textbooks, and interactive tools. The problem is no longer a lack of resources — it is knowing which ones are worth your time.

This guide covers the best websites for learning mathematics in 2026, organized by what they offer and who they serve. Whether you are a first-year student trying to build foundations or a graduate student exploring new areas, there is something here for you.

---

Interactive Learning Platforms

Khan Academy

Khan Academy remains one of the best free platforms for learning mathematics from arithmetic through early university courses. The platform covers:

• Pre-algebra through multivariable calculus
• Linear algebra and differential equations
• Statistics and probability
• AP and competition math preparation

Each topic includes short video lessons, practice problems with instant feedback, and progress tracking.

Brilliant

Brilliant takes a problem-first approach to learning mathematics. Rather than watching lectures, you solve carefully designed interactive problems that build intuition.

Topics range from number theory and combinatorics to group theory and differential equations. The problems are well-crafted and often surprising. Brilliant does require a paid subscription for full access, but the free tier offers a generous daily problem selection.

3Blue1Brown (Grant Sanderson)

While technically a YouTube channel, 3Blue1Brown deserves special mention for its website, which organizes the full library of visual mathematics lessons. The "Essence of Linear Algebra" and "Essence of Calculus" series are genuinely transformative for building geometric intuition.

The animations help you see what linear transformations do, why the determinant measures area scaling, and how derivatives relate to tangent lines — all in a way that textbooks often fail to convey.

---

University-Level Lecture Notes and Courses

MIT OpenCourseWare

MIT OpenCourseWare provides free access to course materials from MIT, including:

• Full lecture notes and problem sets
• Video lectures for many courses
• Exams with solutions

Key mathematics courses include 18.01 (Single Variable Calculus), 18.02 (Multivariable Calculus), 18.06 (Linear Algebra with Gilbert Strang), 18.100 (Real Analysis), and 18.700/18.701 (Algebra). The 18.06 linear algebra course taught by Gilbert Strang is arguably the most famous mathematics course on the internet.

Coursera and edX

Both Coursera and edX host university-level mathematics courses from institutions worldwide. Notable offerings include:

• Imperial College London's "Mathematics for Machine Learning" specialization on Coursera
• Harvard's "Abstract Algebra" on edX
• University of London's "Introduction to Mathematical Thinking" on Coursera

Most courses can be audited for free, with certificates available for a fee.

Paul's Online Math Notes

Paul's Online Math Notes by Paul Dawkins at Lamar University is a long-standing resource that covers:

• Algebra and trigonometry review
• Calculus I, II, and III
• Differential equations

The notes are exceptionally clear, with detailed worked examples and practice problems. This site has helped millions of students through their calculus courses.

---

Research-Level and Advanced Resources

arXiv

arXiv is the primary preprint server for mathematics research. Nearly every new paper in mathematics appears here before (or instead of) formal journal publication. The math section is organized into subcategories like math.AG (Algebraic Geometry), math.AT (Algebraic Topology), math.NT (Number Theory), and many more.

Learning to navigate arXiv is an essential skill for any student considering graduate school. We cover this in detail in our guide to using arXiv effectively.

MathOverflow

MathOverflow is a question-and-answer site for professional mathematicians and advanced graduate students. Unlike Mathematics Stack Exchange (which serves all levels), MathOverflow focuses on research-level questions. Reading discussions here can give you a sense of how working mathematicians think about problems.

nLab

nLab is a collaborative wiki focused on higher category theory, homotopy theory, and related areas of mathematics and mathematical physics. It is extremely detailed and assumes significant background, but for graduate students working in these areas, it is an invaluable reference.

---

Problem-Solving and Competition Resources

Art of Problem Solving (AoPS)

Art of Problem Solving is the premier community for mathematical problem-solving. Originally focused on competition mathematics, AoPS has expanded to include:

• A comprehensive wiki with topic articles and problem solutions
• Online courses for competition preparation
• Active forums where students discuss problems
• The Alcumus adaptive problem-solving system

The AoPS community forums contain solutions to problems from AMC, AIME, USAMO, IMO, and Putnam, making it an incredible archive for anyone who wants to improve their problem-solving skills.

Project Euler

Project Euler offers hundreds of computational problems that require both mathematical insight and programming skills. Problems like "Find the sum of all primes below two million" or "How many $n$-digit numbers are also an $n$th power?" combine number theory, combinatorics, and algorithmic thinking.

This site is especially valuable for students interested in computational mathematics or anyone who wants to practice thinking about mathematics through code.

---

Reference Websites

Wolfram MathWorld

MathWorld is a comprehensive encyclopedia of mathematics maintained by Wolfram Research. It covers thousands of topics with precise definitions, formulas, and references. When you need a quick reference for a theorem statement, a formula, or the definition of a mathematical concept, MathWorld is often the fastest source.

The On-Line Encyclopedia of Integer Sequences (OEIS)

The OEIS is one of the most unique resources in mathematics. If you encounter a sequence of integers in your work — say $1, 1, 2, 5, 14, 42, \ldots$ — you can search for it on the OEIS and immediately find that these are the Catalan numbers, along with dozens of references, formulas, and related sequences.

Wikipedia (Mathematics Portal)

The Wikipedia Mathematics Portal provides surprisingly high-quality articles on mathematical topics. Many articles are written or edited by professional mathematicians and include detailed proofs, history, and references. For an overview of a new topic, Wikipedia is often the best starting point.

---

Interactive and Visual Tools

Desmos

Desmos is a free online graphing calculator that excels at visualizing functions, parametric curves, and inequalities. You can plot $f(x) = \sin(x)/x$, animate parameters with sliders, and share your graphs via URL.

GeoGebra

GeoGebra is a more comprehensive tool that combines geometry, algebra, calculus, and 3D visualization. It is especially useful for:

• Exploring geometric constructions interactively
• Visualizing surfaces like $z = x^2 + y^2$ in 3D
• Creating demonstrations for presentations

Both tools are covered in detail in our guide to GeoGebra and Desmos.

---

How to Use These Resources Effectively

Having access to all these websites does not automatically make you a better mathematician. Here are some principles for getting the most out of them:

1. Do Not Just Watch — Do

Watching a 3Blue1Brown video or reading a MathWorld article feels productive, but real learning comes from working through problems yourself. Use videos and articles to build intuition, then sit down with pen and paper.

2. Pick One Primary Resource Per Course

If you are studying real analysis, do not try to follow five different sets of lecture notes simultaneously. Pick one primary source (a textbook or a course) and use other resources as supplements when you get stuck on a specific topic.

3. Use Forums Wisely

Mathematics Stack Exchange and AoPS forums are enormously helpful, but resist the urge to look up solutions immediately. Struggle with problems first. When you do ask for help, show your work and explain where you are stuck.

4. Build a Personal Library of Bookmarks

Create a structured collection of bookmarks organized by topic. When you find a particularly clear explanation of, say, the Heine-Borel theorem or the isomorphism theorems, save it. Over time, this becomes your personal reference library.

5. Contribute Back to the Community

Once you have learned enough, consider answering questions on Mathematics Stack Exchange, editing Wikipedia articles, or writing your own notes. Teaching others is one of the most effective ways to solidify your own understanding.

---

A Quick Comparison Table

---

Final Thoughts

The landscape of online mathematics resources has never been richer. The websites listed here represent the best of what is available — tools and communities that have genuinely helped millions of students learn mathematics more deeply.

The key is to be intentional about how you use them. Resources are most valuable when they complement active study, not when they replace it. Choose wisely, practice deliberately, and remember that the goal is understanding, not just exposure.

---

References

• Khan Academy — Mathematics
• Brilliant — Math Courses
• 3Blue1Brown
• MIT OpenCourseWare — Mathematics
• Coursera — Mathematics Courses
• edX — Mathematics Courses
• Paul's Online Math Notes
• arXiv — Mathematics
• MathOverflow
• nLab
• Art of Problem Solving
• Project Euler
• Wolfram MathWorld
• OEIS — On-Line Encyclopedia of Integer Sequences
• Wikipedia Mathematics Portal
• Desmos Graphing Calculator
• GeoGebra