Pinyinizer offers a functionality to detect 汉字 (Hanzi) on a webpage and annotate them with corresponding 拼音 (Pinyin) as ruby.
You can use the extension on any webpage. Just click the icon, and 汉字 on the page will be get annotated!
I developed the extension mainly for the purpose of learning Chinese language. I would be happy if Chinese learners enjoy using it. 一起加油吧 :)