This table is a ranked catalogue of mathematics-learning websites covering primary school through higher mathematics. It shows the educational level, subject coverage, availability of exercises, interactive tools, worked solutions, access model, current status, and the best use of each resource. It also identifies obsolete websites and suggests modern replacements.
Together, these resources form a practical alternative to Brilliant.org. Khan Academy and CK-12 provide structured courses; GeoGebra, Desmos, Mathigon, and Seeing Theory provide interactive visualization; Art of Problem Solving develops deeper problem-solving skills; and MIT OpenCourseWare, OpenStax, LibreTexts, and Paul’s Online Math Notes support college-level study. Most are free and do not require a recurring subscription. The main trade-off is that Brilliant offers these functions within one polished platform, whereas this catalogue requires using several specialized websites.
| Rank | Website | Current URL | Status | Level(s) | Primary topic / scope | Exercises | Interactive | Solutions | Access | Best use / comments | List origin | Verification source |
| 1 | Khan Academy | https://www.khanacademy.org/math | Active | Primary; Middle school; High school; College level | Structured mathematics courses from early arithmetic through calculus and linear algebra | Yes | Yes | Yes | Free | Best all-round structured self-study resource; mastery practice and progress tracking. | Original | https://www.khanacademy.org/math |
| 2 | GeoGebra | https://www.geogebra.org/math | Active | Primary; Middle school; High school; College level | Geometry, algebra, graphing, calculus, statistics, simulations and classroom activities | Yes | Yes | Varies | Free | Best general-purpose visualization and mathematical experimentation platform. | Original | https://www.geogebra.org/math |
| 3 | Art of Problem Solving / Alcumus | https://artofproblemsolving.com/alcumus | Active | Middle school; High school; College level; Higher math | Deep problem solving, contest mathematics, algebra, geometry, number theory and combinatorics | Yes | Yes | Yes | Free core resources; paid courses/books | Excellent for rigorous reasoning and challenging problems; substantially harder than ordinary school practice. | Added | https://artofproblemsolving.com/resources |
| 4 | MIT OpenCourseWare — Mathematics | https://ocw.mit.edu/search/?d=Mathematics | Active | College level; Higher math | University mathematics courses including calculus, linear algebra, differential equations, analysis and applied mathematics | Yes | Limited | Often | Free | Best free university-level course archive; availability of solutions varies by course. | Added | https://ocw.mit.edu/collections/ocw-scholar/ |
| 5 | Paul's Online Math Notes | https://tutorial.math.lamar.edu/ | Active | High school; College level | Algebra, Calculus I–III, differential equations and selected PDE topics | Yes | No | Yes | Free | Exceptionally useful written notes, worked examples and practice problems for calculus and differential equations. | Original | https://tutorial.math.lamar.edu/ |
| 6 | NRICH | https://nrich.maths.org/ | Active | Primary; Middle school; High school | Curriculum-linked mathematical problem solving for ages 3–18 | Yes | Some | Yes | Free | Best for non-routine problems, mathematical thinking and classroom enrichment. | Added | https://nrich.maths.org/home |
| 7 | Math Is Fun | https://www.mathsisfun.com/ | Active | Primary; Middle school; High school | Arithmetic, algebra, geometry, statistics, puzzles, games and illustrated explanations | Yes | Yes | Yes / varies | Free | Clear explanations and broad school-level coverage; especially good for quick conceptual refreshers. | Original | https://www.mathsisfun.com/links/index.html |
| 8 | OpenStax Mathematics | https://openstax.org/subjects/math/ | Active | High school; College level | Peer-reviewed open textbooks in algebra, precalculus, calculus, statistics and related subjects | Yes | Limited | Yes / varies | Free | Best source of complete, textbook-style courses without a subscription. | Added | https://openstax.org/subjects/math/ |
| 9 | Desmos | https://www.desmos.com/ | Active | Middle school; High school; College level | Graphing, geometry, 3D visualization and interactive classroom activities | Some | Yes | Limited | Free | Excellent for graphing and visual intuition; not a complete curriculum by itself. | Added | https://www.desmos.com/ |
| 10 | CK-12 FlexMath | https://flexmath.ck12.org/ | Active | Primary; Middle school; High school | Customizable digital textbooks, adaptive practice and interactive mathematics resources | Yes | Yes | Yes / feedback | Free | Strong school-level alternative to Khan Academy, with textbooks and adaptive practice. | Added | https://flexmath.ck12.org/ |
| 11 | Mathigon | https://mathigon.org/ | Active | Middle school; High school | Interactive courses, manipulatives and explorations in algebra, geometry, probability, graph theory and cryptography | Some | Yes | Partial | Free | Highly polished visual and exploratory learning; coverage is selective rather than comprehensive. | Added | https://mathigon.org/ |
| 12 | MyOpenMath | https://www.myopenmath.com/info/selfstudy.php | Active | High school; College level | Online homework, quizzes, tests and self-study courses tied to open textbooks | Yes | Yes | Yes / settings vary | Free | Best as a practice and assessment system, particularly for developmental and college mathematics. | Original | https://www.myopenmath.com/info/selfstudy.php |
| 13 | Mathematics LibreTexts | https://math.libretexts.org/ | Active | High school; College level; Higher math | Open textbooks and course materials across algebra, calculus, analysis, statistics and advanced subjects | Yes | Some | Often | Free | Very broad open library; quality and completeness vary by book or course. | Added | https://math.libretexts.org/ |
| 14 | Math Insight | https://mathinsight.org/ | Active | High school; College level | Conceptual explanations and interactive applets, especially multivariable calculus, vectors and dynamical systems | Yes | Yes | Yes / varies | Free | Excellent visual supplement for vector calculus and differential-equation intuition. | Original | https://mathinsight.org/about/mathinsight |
| 15 | 3Blue1Brown | https://www.3blue1brown.com/topics | Active | High school; College level; Higher math | Visual explanations of calculus, linear algebra, differential equations, probability, topology and other topics | No | Limited | No | Free | Among the best resources for intuition, but should be paired with exercises and a textbook. | Added | https://www.3blue1brown.com/topics/linear-algebra |
| 16 | Wolfram Demonstrations Project | https://demonstrations.wolfram.com/topics/mathematics | Active | Middle school; High school; College level; Higher math | Interactive demonstrations across school mathematics, calculus, discrete mathematics and advanced topics | No | Yes | No | Free viewing; some Wolfram features may require software/account | Large visualization library; better for exploration than sequential learning. | Original | https://demonstrations.wolfram.com/topics/mathematics |
| 17 | Brilliant | https://brilliant.org/math/ | Active | Middle school; High school; College level | Interactive mathematics, logic, probability, calculus and applied problem solving | Yes | Yes | Yes | Freemium; full access requires subscription | High-quality interactive learning, ranked lower here because the strongest access is subscription-based. | Added | https://brilliant.org/math/ |
| 18 | Harvey Mudd Calculus Tutorials | https://math.hmc.edu/calculus/ | Active | High school; College level | Precalculus, single- and multivariable calculus and selected linear algebra tutorials | Limited | Limited | Limited | Free | Useful concise tutorials for specific topics; not a complete exercise-driven course. | Original | https://math.hmc.edu/calculus/ |
| 19 | Seeing Theory | https://seeing-theory.brown.edu/ | Active | High school; College level | Probability and statistics through interactive visualizations | No | Yes | No | Free | Outstanding visual introduction to probability and statistics; narrow but excellent. | Added | https://seeing-theory.brown.edu/ |
| 20 | Purplemath | https://www.purplemath.com/modules/index.htm | Active | Middle school; High school | Prealgebra, algebra and selected precalculus lessons with worked examples | Limited | No | Worked examples | Free | Good text-based algebra explanations; less interactive and less systematic than modern course platforms. | Original | https://www.purplemath.com/modules/index.htm |
| 21 | Wolfram MathWorld | https://mathworld.wolfram.com/ | Active | High school; College level; Higher math | Mathematics encyclopedia and technical reference | No | No | No | Free | Excellent reference for definitions, formulas and advanced topics; not designed as a teaching course. | Original | https://mathworld.wolfram.com/about/ |
| 22 | Logitext | https://logitext.mit.edu/ | Active | College level; Higher math | Interactive proof assistant and tutorial for first-order classical logic and sequent calculus | Yes | Yes | Yes / proof feedback | Free | Specialized but valuable introduction to formal logic and proof construction. | Original | https://logitext.mit.edu/main |
| 23 | MathCS.org | https://mathcs.org/ | Active | College level; Higher math | Interactive real analysis, statistics and developing complex-analysis material | Yes | Limited / legacy | Yes / varies | Free | Substantial advanced material, but some interactive components are legacy Java-era tools. | Original | https://mathcs.org/ |
| 24 | Mathopolis | https://www.mathopolis.com/ | Active | Primary; Middle school | Basic mathematics games, quizzes and question database | Yes | Yes | Yes / feedback | Free | Useful for basic skills and lightweight practice; narrower than Math Is Fun or Khan Academy. | Original | https://www.mathopolis.com/about.php |
| 25 | MacTutor History of Mathematics | https://mathshistory.st-andrews.ac.uk/ | Active | High school; College level; Higher math | Biographies, historical essays and supporting material on mathematics | No | No | No | Free | Authoritative and extensive history-of-mathematics reference, not an exercise site. | Original | https://mathshistory.st-andrews.ac.uk/ |
| 26 | MIT Mathlets | https://mathlets.org/mathlets/ | Active | High school; College level | JavaScript applets for differential equations, calculus and related mathematical subjects | Some activities | Yes | Some guides | Free | Strong specialized visualizations, especially for differential equations; the original MIT URL has moved. | Original — updated URL | https://mathlets.org/ |
| 27 | Interactive Gallery of Quadric Surfaces | https://www-users.cse.umn.edu/~rogness/quadrics/ | Active but legacy | College level | Interactive gallery of ellipsoids, paraboloids, hyperboloids, cones and cross-sections | No | Yes / legacy | No | Free | Narrow but still useful for multivariable-calculus visualization; interface shows its age. | Original — updated URL | https://www-users.cse.umn.edu/~rogness/quadrics/ |
| 28 | Grey Matters: Mental Gym | https://gmmentalgym.blogspot.com/ | Archive / inactive | Middle school; High school | Mental mathematics, recreational puzzles, memory exercises and quizzes | Yes | Yes | Yes / feedback | Free | Still accessible, but the blog appears inactive and is best treated as an archive. | Original | https://gmmentalgym.blogspot.com/ |
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