ColorHexa https://www.colorhexa.com
Colors.css http://clrs.cc
ColorPick Eyedropper extension https://chrome.google.com/webstore/detail/colorpick-eyedropper/ohcpnigalekghcmgcdcenkpelffpdolg?hl=en
Coolors https://coolors.co
Palettte https://palettte.app
Material UI Colors https://materialuicolors.co/
Color Supply http://colorsupplyyy.com/app/
Color Safe http://colorsafe.co
Color Hunt http://www.colorhunt.co
Open Color https://yeun.github.io/open-color/
HTML Color Codes http://htmlcolorcodes.com/
Adobe Color CC https://color.adobe.com/create/color-wheel/
1stwebdesigner的文章： https://1stwebdesigner.com/web-based-color-tools/