Is there any free or cheap editor for Windows, that would allow to edit files with .woff extension (I checked in css that the font file has woff extension). These are fonts offered by Google Webfonts and they are free to embed, modify etc. I'd like to only add diacritic accents to some letters for specific language and embed the font on a website.
Convert the 'woff' webfont to a regular font (e.g. TTF) using a service such as Online Font Converter. Then edit the converted file with your favorite font editing software.
Specific 'woff' Editor:
http://www.high-logic.com/font-editor/fontcreator.html
Programming Tools: