https://ngn.codeberg.page/k/#eJxdjssKwjAQRffzFddVFyLFoiiFQD8...
https://www.jsoftware.com/#/
kona : https://github.com/kevinlawler/kona
alto a javascript implementation even with a graphics library : https://github.com/JohnEarnest/ok
edit : assuming you were talking about k and not freq
My maths notebook from high school looked like that. I'm having flashbacks. (At least in text files you can't cram 4 lines of text into 1.)
https://code.jsoftware.com/wiki/Essays/Incunabulum
https://ngn.codeberg.page/k/#eJxdjssKwjAQRffzFddVFyLFoiiFQD8...