The W3C Markup Validation Service
This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. If you wish to validate specific content such as RSS/Atom feeds or CSS stylesheets, MobileOK …
Free Online HTML Validator - FreeFormatter.com
This free online HTML validator lets you validate your files against the w3c standards
HTML Validator - HTMLStrip
It is a simple free HTML validator which is based on specifications provided by w3.org. This tool provides guidance on markup errors and best practices on Web documents in HTML, XHTML, SMIL, MathM …
HTML Validator - static.app
Validate HTML code online with our free HTML Validator. Ensure your code is error-free and compliant with the latest web standards.
validator.w3.com
Online tool for validating web documents against W3C standards.
HTML Validator Online - AppDevTools
HTML Validator is a free online developer tool to validate HTML code against the W3C standards as known as HTML linter instantly. Supports partial HTML code validation. You can either browse an …
Free email address validator - Verifalia
Verifalia's free email verification service: check if an email address is valid and properly formatted, really exists and can accept mails, plus a lot more!