HEATKEYS

Free cross-platform web-based Online XML Editor, runs on Linux, Windows, Mac, FireFox, Chrome, IE. Edit XML schema or document. No user registration required.

A web-based XML validator. Can be used for free. Validates XML files, prompts the user for referenced files (e. g., XSD), shows good error messages.

Online tools for developers, including formatters (JSON, XML, HTML, SQL, etc.), minifiers (JavaScript, CSS), validators, compactors and many more!

HTML XHTML CSS JavaScript XML XSL ASP SQL ADO VBScript Tutorials References Examples

An online XML formatter.

Generate and Edit XML Sitemaps, Html and Text Sitemaps Free Online

XML.com, where the XML community shares XML development resources and solutions, features timely news, opinions, features, and tutorials; the Annotated XML specification created by Tim Bray; authoring tools, XML developer resources, interactive forum...

Web Design and HTML are all about creating a great Web site. Use Web development and Web site design to build Web sites that customers return to over and over again. On this site learn the basics of Web design, HTML, XML, and Web development.

W3C

Tools to allow simple testing of xpath expressions online on live XML content