There are browser plugins such as Spectrum [1] that might be more useful.
[1] https://chrome.google.com/webstore/detail/spectrum/ofclemegk...
Last year I wrote a small bookmarklet for doing live, on-site color blindness simulation:
https://github.com/jaz303/ColorScope.js
It's by no means foolproof but I've found it useful for testing sites in development.
But there is no such way to test a site persay, only upload individual images.