Free On-the-Web HTML Validators and Link Checkers
Site Check – Type in one URL and automatically run HTML and stylesheet validators, accessibility assessment, link check, load time check, and more. Organizes access to a collection of free online web test tools. Site of UITest.com/Jens Meiert. Also lists a wide variety of free online web analysis/development/test tools.
Link Valet – Online link checker, includes capability fot hilight links modified since a specified date.
Dead-Links.com – Free link-checker limited to 25 pages per domain and 150 external documents. Higher limits if site has a link to Dead-Links.com.
WDG HTML Validator – Web Design Group’s validator – latest HTML version support, flexible input methods, user-friendly error messages.
Web Page ‘Purifier’ – Free on-the-web HTML checker by DJ Delorie allows viewing a page ‘purified’ to HTML 2.0, HTML 3.2, HTML 4.0, or WebTV 1.1. standards.
W3C HTML Validation Service – HTML validation site run by the WWW Consortium (the folks who set web standards); handles one URL at a time; Can choose from among 30 character encoding types, and multiple HTML and XHTML document types/versions.
W3C CSS Validation Service – CSS validation site run by the WWW Consortium (the folks who set web standards); handles one URI at a time; or upload file or validate by direct input.
W3C Link Checker – Link checking service run by the WWW Consortium (the folks who set web standards); configurable. Handles one URL at a time. PERL source also available for download.
Weblint Gateway – Site with online HTML validator; somewhat configurable. Site provided by San Francisco State University.
Web Page Backward Compatibility Viewer – On-the-web HTML checker by DJ Delorie; will serve a web page to you with various selectable tags switched on or off; very large selection of browser types; to check how various browsers or versions might see a page.