Math Blogs and Public Writing Sites

• Quanta Magazine
• The Accidental Mathematician by Izabella Laba
• mathbabe

Math Notes

• The Stacks project (almost all of mathematics)
• Kerodon (Higher Category Theory)
• The CRing Project (Open source commutative algebra textbook)
• Expository Papers on Topics by Keith Conrad

LaTeX

• List of LaTeX symbols
• Detexify
• tikzcd-editor

Forums

• Mathematics Stack Exchange
• MathOverflow
• TeX - LaTeX Stack Exchange

Yiddish (יידיש)

• The Yiddish League (די יידיש–ליגע)
• Yiddish Book Center (דער יידישער ביכער צענטער)
• Workers Circle (דער אַרבעטער רינג)
• Yiddish Pop (Cute Yiddish childrens videos)
• Kinder-loshn (קינדער לשון)
• Olniansky (New Yiddish books)
• Pink Peacock (Yiddish, Anarchist cafe)