Usability and accessibility are two very important topics in web design. When building a website you should try to support as many possible devices and browsers as possible.
But what about people with disabilities who also browse the web? This is the whole idea behind accessible websites and accessibility testing.
A cool Google Chrome extension named Colorblinding is one tool made to help with accessibility tests for colorblind visitors. This allows you to approximate how colorblind people may see your page(s).
From this you can determine issues with contrast, size, and relationships of page elements. If you site pulls a large number of people each month then you really need to consider if testing will improve the overall UX of your audience.
You can install Colorblinding completely free from the Chrome web store. It can work on any website and works across a handful of color spectrums.
Plus you developers might like to know that Colorblinding is open source on GitHub with room for improvements.
But anyone can try this out and even see how it works on some of your favorite websites.