[gradientsrneat]

Sad that the Wikipedia page links to some specific commercial service rather than the actual programming language runtime (which appears to be AGPL-licensed).

[sossupummi]

you can still try it out here https://kparc.io/kc/

other versions (not k7) include eg. https://ktye.github.io/k.html

[tosh]

the original implementations of k were all proprietary

there are a few open source implementations as well by now

https://wiki.k-language.dev/wiki/Running_K