1. XML Validation Form
While Extended Mark-up Language (XML) platform is still being developed, designers can check their code compliance with this free service.
http://www.stg.brown.edu/service/xmlvalid http://www.stg.brown.edu/service/xmlvalid

2. XML Schema (REC (20010502) version, as amended) Checking Service
XML LTG Validator for XML Schema REC (20010502) version , as amended XSV version: XSV 2.10-1 of 2005/ 04/22 13:10:49 NOTICE: This is a service for a W3C approved recommendation. This ...
http://www.w3.org/2001/03/webdata/xsv http://www.w3.org/2001/03/webdata/xsv

3. HTML / XHTML / XML / WML Validator
HTML / XHTML / WML / XML Validator de | en | fr | ru Resources | Sidebar | Contact | About auto detect HTML 4.01 Transitional HTML 4.01 Strict HTML 4.01 Frameset HTML 4.0 Transitional HTML ...
http://www.validome.org http://www.validome.org

4. XSD Schema Validator
XSD Schema Validator. Schema document: NamespaceURI: XML document: This page allows you to validate an XML documents against an W3C XML Schema...
http://apps.gotdotnet.com/xmltools/xsdvalidator http://apps.gotdotnet.com/xmltools/xsdvalidator

5. XML Well-Formedness Checker and Validator
Checks an XML document (specified by URL) for well-formedness and optionally DTD-based validity and namespace correctness. Outputs canonical XML. Runs over the web and can be downloaded.
http://www.cogsci.ed.ac.uk/~richard/xml-check.html http://www.cogsci.ed.ac.uk/~richard/xml-check.html

6. ElCel Technology
Education and consultancy support includes DTD and schema construction, content management, and messaging. Download an XML validator and canonical processor.
http://www.elcel.com http://www.elcel.com

7. AspXer
C# program to convert simple HTML forms to ASPX form controls, and does double duty as an XML validator.
http://www.compumagic.com/AspXer http://www.compumagic.com/AspXer

8. XML Schema Validator, DTD Validator
... XML Overview XML Editing Views XML Grid View Sense:X Intelligent XML Editing XML Schema/DTD Validator XML Differencing XML Parsers Well Formedness Checker XML Document Wizards Project ...
http://www.stylusstudio.com/xml_validation.html http://www.stylusstudio.com/xml_validation.html

9. XML DTD
A general XML Validator. To help you check the syntax of your xml files, we have created this link so that you can syntax-check any XML file.
http://www.w3schools.com/xml/xml_dtd.asp http://www.w3schools.com/xml/xml_dtd.asp

10. HTML/XHTML/XML validator
Validates and repairs HTML, XHTML, and XML.
http://validator.aborla.net http://validator.aborla.net

11. Topologi Schematron Validator
Shareware that validates XML documents using Schematron, DTDs, and W3C XML Schemas
http://www.topologi.com/products/validator/index.html http://www.topologi.com/products/validator/index.html

12. W3C XML Schema
XML::Validator::Schema. XML::Validator::Schema 1.03. This Perl module allows you to validate XML documents against a W3C XML Schema.
http://www.w3.org/XML/Schema http://www.w3.org/XML/Schema

13. Sun Multi-Schema XML Validator
Sun's MSV is a Java technology tool to validate XML documents against several kinds of XML schemata. It supports RELAX NG, RELAX Namespace, RELAX Core, TREX, XML DTDs, and most of XML Schema.
http://www.sun.com/software/xml/developers/multischema http://www.sun.com/software/xml/developers/multischema

14. XML well-formedness checker and validator
XML well-formedness checker and validator. Use this form to check an XML document for well-formedness and (optionally) validity.
http://www.cogsci.ed.ac.uk/%7Erichard/xml-check.html http://www.cogsci.ed.ac.uk/%7Erichard/xml-check.html

15. W3C - Validator for XML Schema
Check code validity by referencing Web-accessible or uploading original schemas. Output is comprised of an XSLT style sheet differentiating warnings and critical errors.
http://www.w3.org/2000/09/webdata/xsv http://www.w3.org/2000/09/webdata/xsv