I wish Haketilo [1] would have caught on more. There's so many free JavaScript apps but we're mostly just missing a way to actually control which version or derivative of the JavaScript is run.

There's also the problem of most free apps not doing a good job of providing license info and a link to source code, but this could be sidestepped by a trusted repository which provides license info itself.

[1] https://haketilo.koszko.org/