Tools to validate HTML

 
  Bobby
Bobby checks html for different browsers.
 

 

  W3C Validator
The Web Consortium's validation service.
  MOMspider
a web robot which checks validity of links.
HTML Tidy
A print utility that will fix many errors and print html code nicely.
  linklint
Linklint is a shareware script which checks for broken links. Can be run under Perl 4 or Perl 5.
NetMechanic
A popular robot based service which offers broken link detection.
 
LinkScan 
LinkScan is another commercial link checker. Good for Unix and Windows NT.
 
  Dr. Watson
A web based checker of HTML.
Doctor HTML
Spellchecker and testing of table structure.
  SWAN - SubWeb ANalyzer
SWAN  analyzes  local subwebs of WWW. 
  HTML PowerTools 
A commercial suite of tools for validation and checking html.