guide

1. html2markdown: pretty old, don't know how to use

2. reverse_markdown

   input  = '<strong>feelings</strong>'
   result = ReverseMarkdown.convert input
   result.inspect # " **feelings** "
   

3. kramdown

   html = 'How to convert <b>HTML</b> to <i>Markdown</i> on <a href="http://stackoverflow.com">Stack Overflow</a>.'
   document = Kramdown::Document.new(html, :html_to_native => true)
   document.to_kramdown
   # "How to convert **HTML** to *Markdown* on [Stack Overflow][1].\n\n\n\n[1]: http://stackoverflow.com\n"
   

   The result is :
   How to convert HTML to Markdown on Stack Overflow.