Multivariable Calculus cain.math.gatech.edu

G. Cain, J. Herod (Georgia Tech).

Byrne's Euclid c82.net

Interactive web edition of Oliver Byrne's color-coded presentation of Euclid's first six books.

Open Logic Textbook builds.openlogicproject.org

collaborative effort, main contributors listed here.

Brilliant brilliant.org

Interactive, problem-based lessons in foundational mathematics, probability, and related quantitative subjects.

Bridges bridgesmathart.org

Annual conference on mathematical connections in art, music, architecture, and culture.

Lecture Notes in Algebraic Topology bookstore.ams.org

Paid textbook by James F. Davis and Paul Kirk.

An Introduction to Complex Analysis and Geometry bookstore.ams.org

Paid textbook by John P. D'Angelo.

b=M²L bm2l.github.io

Barcelona Mathematics and Machine Learning colloquia on the interaction between mathematics and machine learning, with multi-year editions and recorded talks.

Group Theory birdtracks.eu

Predrag Cvitanović.

BetterExplained betterexplained.com

Maintained by Kalid Azad.

Logic and Proof avigad.github.io

Jeremy Avigad, Robert Y. Lewis, and Floris van Doorn.

Galois Theory arxiv.org

Tom Leinster (University of Edinburgh).

Foundations of Constructive Probability Theory arxiv.org

Yuen-Kwok Chan.

Seven Sketches in Compositionality: An Invitation to Applied Category Theory arxiv.org

Brendan Fong and David I. Spivak (MIT).

Harmonic Analysis Lecture Notes arxiv.org

Richard S. Laugesen (University of Illinois at Urbana-Champaign).

Theory of Statistics archive.math.arizona.edu

Graduate notes by Joseph C. Watkins on measure-based probability, decision theory, estimation, testing, and hierarchical models.

Lectures on Statistics archive.math.arizona.edu

Free text by William G. Faris covering inference, Bayesian methods, regression, principal components, and linear models.

Intuitionistic Type Theory archive-pml.github.io

Per Martin-Lof.

Functional Analysis: Lecture Notes apps.math.msu.edu

Jeff Schenker (Michigan State University).

Applied Combinatorics appliedcombinatorics.org

Mitchel T. Keller, William T. Trotter.

AMS Open Math Notes ams.org

Free course notes, textbooks, and research expositions hosted by the American Mathematical Society.

Notices of the American Mathematical Society ams.org

Publicizes activities of the Society and features surveys, reports, news, announcements, and opinions on industry trends, academia, and research.

Bulletin of the American Mathematical Society ams.org

Expository articles on contemporary mathematical research, written in a way that gives insight to mathematicians who may not be experts in the particular topic.

Almost Fun almostfun.org

Free interactive middle- and high-school mathematics lessons, practice problems, and teacher resources from a nonprofit organization.

Analytic Combinatorics algo.inria.fr

Philippe Flajolet, Robert Sedgewick.

Algebraic Geometry agag-gathmann.math.rptu.de

Andreas Gathmann (RPTU).

Stochastic Processes adembo.su.domains

Amir Dembo (Stanford University).

Natural Number Game adam.math.hhu.de

Interactive Lean 4 game that introduces theorem proving through guided exercises about natural numbers.

Category Theory academic.oup.com

Paid textbook by Steve Awodey.

3Blue1Brown 3blue1brown.com

Animated explanations of mathematics by Grant Sanderson.

First Proof Project 1stproof.org

Independent project that publishes research-level problems, evaluation methods, solutions, and expert commentary for assessing AI systems in mathematics.

Yoast SEO wordpress.org

Improve your WordPress SEO: Write better content and have a fully optimized WordPress site using Yoast SEO plugin.

Slim SEO wordpress.org

Automated SEO tasks for you with a lightweight WordPress SEO plugin.

All in One SEO Pack wordpress.org

The most downloaded plugin for WordPress (almost 30 million downloads). Use All in One SEO Pack to automatically optimize your site for Search Engines.

HTTPS webmasters.googleblog.com

Security is a top priority for Google.

SEO for Web Designers webdesign.tutsplus.com

SEO for Web Designers with Craig Campbell by TutsPlus.

WAI-Aria w3.org

Use WAI-Aria tags to help machines understand your code.

Responsive Images w3.org

Serve the most optimized image corresponding to the window size.

Learning Web Analytics video2brain.com

Learning Web Analytics with Matt Bailey by video2brain.

Learning Search Engine Optimization (SEO) - A Video Introduction video2brain.com

Learning Search Engine Optimization (SEO) - A Video Introduction with Matt Bailey by video2brain.

Varvy Seo tool varvy.com

Displays: domain strength, links, image seo, social counts & mentions, page/technical seo, pagespeed and more.

HTML Validator validator.w3.org

CSS Validator).

SEO Training Course by Moz udemy.com

SEO Training Course with Moz by udemy.

Basic SEO Features typo3.org

Adds a separate field for the title-tag per page, easy and SEO-friendly keywords and description editing in a new module as well as a flexible Google Sitemap.

Google sitemap typo3.org

High performance Google sitemap implementation that avoids typical errors by other similar extensions.

SEO Bookmarklet twkm.ca

A One-Stop SEO Bookmarklet to Quickly Review On-Site SEO.

Search Engine Spider Simulator tools.seochat.com

This tool simulates a search engine by displaying the contents of a web page in exactly the way the search engine bot would see it when it crawls the page: See most prominent or inaccessible page elements.

nofollow support.google.com

Add rel="nofollow" attribute to external links only to prevent spam and bad links.

Video sitemap support.google.com

Make sure, search engines know about all the video content on your site.

Localisation support.google.com

Choose a country-specific domain, for better local search results.