html-sanitizer is a whitelist-based and very opinionated HTML sanitizer
that can be used both for untrusted and trusted sources. It attempts to
clean up the mess made by various rich text editors and or copy-pasting
to make styling of webpages simpler and more consistent. It builds on the
excellent HTML cleaner in lxml to make the result both valid and safe.

It goes further than pure tag filtering by transforming the HTML
fragments to normalize formatting and drop redundant or pointless tags.