Palette Maker alternatives

Despite its advanced capabilities, the tool is intuitive and easy to navigate, which made onboarding quick and seamless

This tool has been created ages ago, but it just plain works. If you can have the image URL ending in .jpg, just add it to the tool, and there you go: 10 most used colors get extracted. Obviously, the UI is from another era, it can't process pics that as embedded in pages via complex plugins etc. But it doesn't matter.