I am working on a project where I am parsing HTML documents and inserting JavaScript/HTML into the document. I tried to use HTML::TreeBuilder, but it could not support languages other than English. Non-English documents would have garbage characters in the document when it was saved.

I am open to doing this in C++ or Perl.

Does anyone have any experience in creating IE/FireFox plugins? I would like to either have this working as a proxy or browser plugin.

Any assistance is greatly appreciated. Thanks.