A HTML to Markdown converter.

> gem install upmark

In ruby:

require "upmark"
html = "<p>messenger <strong>bag</strong> skateboard</p>"
markdown = Upmark.convert(html)
puts markdown

From the command-line:

> upmark foo.html

You can also pipe poorly formatted HTML documents through tidy before piping them into upmark:

> cat bar.html | tidy -asxhtml -indent -quiet --show-errors 0 --show-warnings 0 --show-body-only 1 --wrap 0 | upmark

Upmark will convert the following (arbitrarily nested) HTML elements to Markdown:

• strong
• em
• p
• a
• h1, h2, h3, h4, h5, h6
• ul
• ol
• br

It will also pass through block and span-level HTML elements (e.g. table, div, span, etc) which aren't used by Markdown.

Upmark defines a parsing expression grammar (PEG) using the very awesome Parslet gem. This PEG is then used to convert HTML into Markdown in 4 steps:

1. Parse the XHTML into an abstract syntax tree (AST).
2. Normalize the AST into a nested hash of HTML elements.
3. Mark the block and span-level subtrees which should be ignored (table, div, span, etc).
4. Convert the AST leaves into Markdown.