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Xmlvalidation
xmlvalidation.com
Validate XML files
Use our tool to quickly validate your XML files against standard syntax or custom schemas.
An example
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.
Documentation
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.
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JSON Formatter
jsonformatter.org β€Ί xml-validator
Best XML Validator Online
XML Validator Online helps to Edit, View, Analyse XML data along with formatting XML data.
Discussions

Does anyone know how to validate XML in VScode?

No, but the W3C Validation Service validates XML against a DTD, I think. I don't know if it can validate against a schema.

Edit: a quick search indicates that there are several NPM packages which will do XML validation. You could write an NPM script that watches for changes to the XML and runs validation, and run that script through the NPM scripts explorer in VSCode.

More on reddit.com
🌐 r/vscode
4
5
November 5, 2016
Are there any free XML editors that you guys extensive use?
Not purely XML editors, but feature-rich text editors I love include: Sublime Text 2 Notepad++ Programmer's Notepad More on reddit.com
🌐 r/xml
4
2
October 26, 2012
XML Validation with Powershell

Very nice, very helpful. I would point out the use add-member for $script:validationresults is deprecated (maybe only for aesthetics?), as PS v3 allows something like this:

$script:validationresults = New-Object PSObject -property @{
  XMLFile = $xmlFile;
  ValidationComplete = $true;
  isValid = $true; 
  Errors = @();
}
More on reddit.com
🌐 r/PowerShell
2
12
January 11, 2012
Perl 5 XML Validation with DTD and XSD
Talking about XML validation: both DTD and XSD are horrible. DTD is very simplistic and forces a specific order of elements, and XSD is bloat and impossible to write. What happened to RelaxNG? That was my favourite. You can write in easily readable compact form, transform it to XML which can be used for validation in XML::LibXML. EDIT: just a clarification: as Gabor Szabo's newsletter summarized your article with "not every liked it (sic)" with a link to this comment section. That's not the case! I liked your article! It's just that I'm not particularly fond of XML. When I ask people why they use it, I often get: "You can validate it!" My next question of course is what they use for validation, on which I usually get a blank stare, which I interpret as: "we could if we wished to so", so the question of which they use - DTD or XSD - answered itself. More on reddit.com
🌐 r/perl
2
8
January 16, 2018
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Liquid Technologies
liquid-technologies.com β€Ί online-xml-validator
Free Online XML Validator (Well formed)
Validates that an XML document is well formed, if you have a schema use the appropriate validator instead (XSD, RelaxNG or Schematron).
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FreeFormatter
freeformatter.com β€Ί xml-validator-xsd.html
Free Online XML Validator Against XSD Schema - FreeFormatter.com
This free online XML validator lets you validate your XML files against an XSD (XML Schema)
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Mockoon
mockoon.com β€Ί tools β€Ί xml-validator
Mockoon - Online XML validator
Mockoon's XML validator tool: validate your XML data in an online editor and get detailed error messages.
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Truugo
truugo.com β€Ί xml_validator
XML Validator - Validate XML Online
Use the XML validator to perform syntax check and to validate XML using schema validation (XSD + DTD). The XML editor helps to fix simple bugs and to beautify/minify your XML output.
Find elsewhere
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Elmah.io
elmah.io β€Ί tools β€Ί xml-formatter
XML Formatter - Free online XML formatter and validator
No matter if you need to do a full validation of an XML file or you simply want to format the elmah.io XML formatter is for you. Get a full overview of why an XML file is invalid and copy a nicely formatted output back to the source file.
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Code Beautify
codebeautify.org β€Ί xmlvalidator
XML Validator Tool to validate XML online: XML Lint
XML Validator Online is easy to use the XML Validate tool. Copy, Paste, and Validate.
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W3C
validator.w3.org
The W3C Markup Validation Service
W3C's easy-to-use markup validation service, based on SGML and XML parsers.
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ReqBin
reqbin.com β€Ί xml-validator
Online XML Validator
August 7, 2023 - Validate XML data strings for XML errors with best-in-class XML linter and XML validator. View XML validation results in an advanced XML editor with built-in syntax highlighting and per-line error indication.
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SAMLTool
samltool.com β€Ί validate_xml.php
Validate SAML XML Using XML Schema (XSD) - Validate XML Against XSD Online Tool
Online tool to validate a SAML XML (Metadata, AuthNRequest, SAML Response, Logout Request and Logout Response) using a XML Schema (XSD).
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CoreFiling
corefiling.com β€Ί home β€Ί open source tools β€Ί online xml schema validator
Free Online XML Schema Validator from CoreFiling
June 20, 2025 - The original and best, world's most popular online XML schema validator. Test your XML against provided or external schema.
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Ecosio
ecosio.com β€Ί startseite β€Ί validate e-invoice & xml files instantly – no signup needed
Free validation service for Peppol, e-invoice and XML documents - no signup needed
September 11, 2025 - Validate e-invoices and other XML documents against every major global standard, from Peppol to XRechnung, in seconds with ecosio’s free XML validator tool.
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Online XML Tools
onlinexmltools.com β€Ί validate-xml
Validate XML - Online XML Tools
This tool validates Extensible Markup Language (XML) documents. If there are errors, this tool will report them.
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BeautifyTools
beautifytools.com β€Ί xml-validator.php
Online XML Validator - BeautifyTools.com
Online XML Validator validates XML markup and makes a list of errors and warnings from your XML code that can be fixed.
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XmlLint
xmllint.com β€Ί home
XmlLint - Awesome XML Formatting & Beautification
September 12, 2021 - Meet XmlLint – a powerful, yet very modern client-only XML formatting and validation tool that can format, validate, or beautify any document or XML snippet (and do it all in a matter of a few seconds)!
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Utilities and Tools
utilities-online.info β€Ί xsdvalidation
W3C XML Schema (XSD) Validation online
Validate XML data against an XSD (XML Schema Definition) to ensure it follows the correct structure and rules.
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Wtools
wtools.io β€Ί validate-xml-online
Validate XML, Online XML Validator | WTOOLS
Validate XML - online web based tool who allows you validate and format XML