For everyone:

• 3Blue1Brown - YouTube channel with videos on various topics of math

• Quanta Magazine - online magazine with articles on recent developments in math (and other sciences)

For mathematicians interested in veering triangulations:

• Census of veering triangulations - up to triangulations with 16 tetrahedra

• Veering - GitHub repository of Python code for working with veering triangulations

• Regina - general program for working with triangulations

For low-dimensional topologists:

• KnotFolio - online tool for identifying knots from drawings, by Kyle Miller

• KnotInfo - database for knots (of ≤ 12 crossings) and their invariants

• The CompuTop.org Software Archive - list of software useful for studying low-dimensional topology