This is a simple JS bookmarklet that will filter the current page according to various colour blindnesses.

The colour blind matrices were sourced from an archived page - http://web.archive.org/web/20081014161121/http://www.colorjack.com/labs/colormatrix/

They may be inaccurate. Corrections welcome.

To use it, simply put the contents of bookmarklet.min.js into a bookmark or go to https://altreus.github.io/colourblind/ to see a demo.

This will only work on browsers that support SVG filters in CSS3 - but you don't really need to cross-browser test it for colourblindness so you only need one such browser.

By which I mean, it works in Chrome and Firefox.