https://susansmathgames.ca/tags/puzzles/
https://mathpickle.com/organized-by-grade/
https://www.jamestanton.com/
https://www.khanacademy.org/
https://nrich.maths.org/
https://math.hmc.edu/funfacts/
https://www.dimensions-math.org/Dim_E.htm
…
www.Brainbashers.com
https://www.geometrygames.org/TorusGames/index.html
https://logicmazes.com/
https://www.puzzlebeast.com/
https://superliminal.com/cube/
https://www.brainbashers.com/puzzles.asp
https://www.brainbashers.com/futoshiki.asp
www.mathinenglish.com/puzzleshidato.php
https://hidato.com/home
www.kenken.com
www.brainbashers.com/neighbours.asp
https://www.mathinenglish.com/puzzlesshikaku.php
http://setgame.com/set/puzzle
https://www.brainbashers.com/skyscrapers.asp
https://www.chiark.greenend.org.uk/~sgtatham/puzzles/