Exercism is a Free Software code learning platform run by a nonprofit. In a lot of ways it's a better alternative to the likes of Hackerrank, Coderbyte, Codecademy, etc. since anyone can become a maintainer of a new language track , and of course there's no profit motive to lock things up behind paywalls.
There's also Lapce which will hopefully implement Helix's editing model too: https://github.com/lapce/lapce/issues/281