Choose your algorithm

W3C has written 2 programs algorithms to check the compliancy of a HTML page.
Both algorithms are included in HTML Validator for Firefox. Both have advantages and incovenients.

tidy
HTML Tidy
sgml
SGML Parser (OpenSP)
Description It is an algorithm designed only for checking the HTML syntax. It is the same algorithm running behind the validator.w3.org
Better for HTML XHTML
Accessibility check a WAI level 1,2,3 -
Cleanup page Yes -
Good help Yes No (Todo)
Clear error messages Yes No
Same errors than the validator.w3.org No Yes
Target Audience Beginner Professional