I think this tool is very useful to check the color contrast of my website. And it seem no other software is better than this tools so far.
Unfortunately, I find this add-on doesn't support the latest Firefox version, I hope there will be a update on this add-on to compatible with the latest Firefox version. Since I believe quite many developer use this tool to check the color on website, like me.
The 'Colour Contrast Analyzer' ignores css background gradients on elements.
This is one of the best add-ins that I have installed, just because of the Colour Contrast Analyser. My color-blind husband can now help more with design because the report shows him which elements fail. It's a definite advantage for WordPress blogs, because add-ins may add styles with poor style definitions that are flagged in the report.