Extract Styles From HTML Docs Quickly: extractCSS
extractCSS is a free and web-based application that is capable of extracting style-related information from HTML.
These include ids, classes + inline styles and the output can be customized too (indent and brackets usage).
The tool is very useful when we quickly create an HTML file with inline styles and want to generate the stylesheet of it.
extractCSS is also open source and it is built with only client-side code.