Html5lib

HTML5lib is a python module for parsing documents.

https://code.google.com/p/html5lib/

html5lib is a python library for parsing "html in the wild". A big advantage of working with html5lib, is that, unlike stricter XML tools, it will accept any input document, even when there are missing or incorrect tags. The library follows the "tolerant" behaviour of most web browsers and is very useful as a bridge between "pages in the wild" and the precision of XML tools like ElementTree.

While html5lib is not part of the standard python distribution, it is 100% "pure python" meaning that it's easy to use across platforms (even without a tool like pip working, you can download and import the library by simply placing it's folder in the same directory as your python script).