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HiFi Toolkit

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I Built a Free Online DTD Validator for XML Developers (No Installation Required)

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As developers, we often work with XML in APIs, configuration files, and data exchange.
And if your XML uses a DTD (Document Type Definition), validation becomes critical.


Recently, while working on a project, I ran into a frustrating issue: my XML wasn’t validating,
and the error messages weren’t helpful.

I tried several online tools, but most of them were:

  • Outdated
  • Slow
  • Confusing
  • Or required software installation


So I decided to build a simple, fast, and free online DTD Validator
that works directly in the browser.


You can try it here:


https://www.hifitoolkit.com/dtd-validator/

What is DTD Validation?

DTD defines the structure of your XML document.

It specifies:

  • Allowed elements
  • Element hierarchy
  • Attributes
  • Data structure


Validation ensures your XML follows these rules.
If it doesn’t, your application may fail.

Example XML with DTD

<!DOCTYPE note [
<!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>
]>

<note>
<to>John</to>
<from>Admin</from>
<heading>Reminder</heading>
<body>Hello World</body>
</note>


This XML is valid.
But if you change the order or remove an element, validation will fail.

That’s where a validator helps.

Why I Built This Tool

My goals were simple:

  • No installation
  • Instant validation
  • Clean interface
  • Free access
  • Beginner friendly

Features

  • Instant XML validation
  • Supports DTD
  • Free to use
  • No login required
  • Works in browser
  • Fast and lightweight

How to Use

  1. Open the tool
    https://www.hifitoolkit.com/dtd-validator/
  2. <li>Paste your XML</li>
    
    <li>Click Validate</li>
    

You’ll see the result instantly.

Who Is This Tool For?

  • Frontend Developers
  • Backend Developers
  • XML Developers
  • Students
  • Beginners

Feedback Welcome


This is part of my free developer tools project.


If you have suggestions, feature requests, or feedback, I’d love to hear them.


Tool link:


https://www.hifitoolkit.com/dtd-validator/

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