It doesn't work for all sites.

Looks like it gets data from cssstats.com:

https://api.cssstats.com/stats/?url=

Which is not very reliable/not able to parse some CSS files/rules (as one of the comments mentioned, !important is a problem)

EDIT: cssstat.com is pretty awesome: https://cssstats.com/stats?url=http%3A%2F%2Fmedium.com&name=...

Looks like the site may be having traffic issues right now, it's unable to fetch my palette from some sites I work on.

Very cool service, nonetheless! I love being able to fetch the palette colors and visualize them on the page here. Looks beautiful. I'm also sort of jealous -- this is a great recruiting tool for designers.

PS: Love the export function!

It doesn't appear to be a traffic issue. It looks like it's breaking when it encounters things like "!important" in a site's CSS.

I was able to pull other sites (though maybe they're cached?) like CNN and Ycombinator