The less valid a web page’s html is the less search engine friendly it is. Bad code, excessive code and dead links confuse search engines.
- HTML validator: W3C Markup Validation Service
- CSS style sheet validator: W3C CSS Validation Service
- CSS Comprehensive Validation: WDG CSS Validation Service
- Single page link validator: W3C Link Validator Service
- Validate WAI – Section 508 Standards, or WCAG 1.0 Priority 1,2,3:HiSoftware Company CynthiaSays Portal
- Feed Validator for Atom and RSS: FEED Validator