A command-line script that shows text changes between two HTML files



Usage: htmldiff version1.html version2.html > diff.html

htmldiff outputs HTML that shows the differences in text between two versions of an HTML document. Differences in markup are not shown.

Original version is from Ian Bicking with changes from Richard Cyganiak.


  • Python 2.7

Using with Mercurial

Put htmldiff on the path, and add the following to ~/.hgrc:

hgext.extdiff =

cmd.htmldiff = htmldiff

Then you can do: hg htmldiff index.html > diff.html


This uses Python's SequenceMatcher, which is generally a bit crap and sometimes misses long possible matches, especially if the long match is punctuated by short non-matches, which happens easily for example if markup is systematically changed. You can try uncommenting the simpler version of the isJunk function in the source to make this slightly better, at the price of less speed and more noise.

Ideas for future improvements

  • Add flag for "accurate" versus "risky" mode, see Limitations above
  • Allow diffing only of a given section by specifying an id
  • Allow input by URL
  • Make a web service


MIT License, see LICENSE.txt.