The addon works fine for its intended purpose, but on some websites it actually completely breaks site functionality.

Examples of things not working with this extension enabled: logging in using BankID on dnb.no, merging pull requests and syncing branches in Bitbucket.

It took me quite some time and some tickets with customer support of various services to figure out the root cause for these issues. Please fix the plugin so that it doesn't generate security errors.

This addon has serious issues. I keep finding that it injects weird code into websites just by the addon being enabled, even if I'm not using it. This results in websites breaking. It's a helpful tool but the addon is annoying to have installed.

Doesn't have nearly enough options. Would like to see Protanomaly, Deuteranomaly, Tritanopia, Tritanomaly, Achromatopsia ,Achromatomaly, and a Low-Contrast option.

It also inserts some weird copyright text into text editors when I'm trying to send messages on my website

I'm a front-end web developper, and since Color Oracle software ceased to function with my setting ("recent Ubuntu versions are not supported"), it was really difficult to test webpages I worked on… So I'm grateful that this add-on exists.

As said by Skylar, there is room for improvement: position:fixed seems not supported, and it would be great to have Tritanopia simulation too. But it's already great as it is - so 5 stars.

It's a simple drop-down to select a color filter. I was getting worried that I wouldn't find an addon for this after trying several that don't work anymore.

It would be great if the color filter persisted across pages. As it is, I have to re-apply the setting every time I click a link. I also noticed that Bootstrap navbars fixed to the top of the viewport scroll away when I turn on a color filter.

Easy to use, does exactly what it claims.