Just as you can use W3C’s validator to help validate your HTML, tools exist to help evaluate the accessibility of your websites. The easiest of these are integrated into the developer tools of your browser. The following video covers using Chrome developer tools to address accessibility bugs:

We’ve also talked about Screen Readers and Magnifiers, which are typically integrated into your operating system. You can use these to experience your web page the same way a disabled user might.

Similarly, a colorblindness simulator can alter the colors in your screen to simulate what a colorblind person might see. A good example is Color Oracle, a free and open-source tool that runs on Windows, Mac, and Linux.