Clean Up HTML in Python

I would suggest Beautifulsoup. It has a wonderful parser that can deal with malformed tags quite gracefully. Once you've read in the entire tree you can just output the result.

from bs4 import BeautifulSoup
tree = BeautifulSoup(bad_html)
good_html = tree.prettify()

I've used this many times and it works wonders. If you're simply pulling out the data from bad-html then BeautifulSoup really shines when it comes to pulling out data.

An example of cleaning up HTML using the lxml.html.clean.Cleaner module.

Requires the lxml module — pip install lxml (it's a native module written in C so it might be faster than pure python solutions).

import sys

from lxml.html.clean import Cleaner


def sanitize(dirty_html):
    cleaner = Cleaner(page_structure=True,
                  meta=True,
                  embedded=True,
                  links=True,
                  style=True,
                  processing_instructions=True,
                  inline_style=True,
                  scripts=True,
                  javascript=True,
                  comments=True,
                  frames=True,
                  forms=True,
                  annoying_tags=True,
                  remove_unknown_tags=True,
                  safe_attrs_only=True,
                  safe_attrs=frozenset(['src','color', 'href', 'title', 'class', 'name', 'id']),
                  remove_tags=('span', 'font', 'div')
                  )

    return cleaner.clean_html(dirty_html)


if __name__ == '__main__':

    with open(sys.argv[1]) as fin:

        print(sanitize(fin.read()))

Check out the docs for a full list of options you can pass to the Cleaner.

There are python bindings for the HTML Tidy Library Project, but automatically cleaning up broken HTML is a tough nut to crack. It's not so different from trying to automatically fix source code -- there are just too many possibilities. You'll still need to review the output and almost certainly make further fixes by hand.