Nvu :: A complete Web Authoring System for Linux desktop users as well as Microsoft Windows and Macintosh users to rival programs like FrontPage and Dreamweaver. Nvu (which stands for "new view") makes managing a web site a snap. Now anyone can create web pages and manage a website with no technical expertise or knowledge of HTML.

HTML Tidy, a HTML syntax checker and pretty printer.

JTidy is a Java port of HTML Tidy, a HTML syntax checker and pretty printer. Like its non-Java cousin, JTidy can be used as a tool for cleaning up malformed and faulty HTML. In addition, JTidy provides a DOM interface to the document that is being processed, which effectively makes you able to use JTidy as a DOM parser for real-world HTML.

DRKSpider will navigate a web site from a given URL, checking internal (and external) links, style sheets, images and other files. Broken links will be reported and the site map displayed in a tree control.
DRKSpider is a free open source software, which means you can use it, modify it and distribute it to your friends, freely.