Your "how it works"[1] page makes it look a little like a cross between Codepen and Google Tag Manager. Is that a fair characterization of what Mods do? I like the 'shared library' idea, that's something GTM makes actively harder.
The editor is similar to CodePen, with the biggest difference being you can easily add what you've built to any website. I haven't ever used GTM but I think the "make changes without re-deploying" approach is conceptually similar.