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100% free · no signupRuns in your browser

XML Validator

Validate XML well-formedness using the browser DOMParser.

Best for: Use it to debug a config, feed, SOAP payload or any XML document.

Complete guide

Input

How it's calculated & sources
The XML Validator uses the standard, deterministic formula, so the same inputs always produce the same result. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is XML Validator?
An XML validator checks whether text is well-formed XML and reports where it breaks.
Why does XML Validator matter?
Well-formed or not. 'Well-formed' means correct tag nesting and syntax - it does not check against a DTD or schema unless you validate separately.
How is XML Validator calculated?
It parses the XML with the browser's parser; a failure returns the line and reason.
What are common xml validator mistakes?
Confusing well-formed with schema-valid.
When should you use the XML Validator?
Use it to debug a config, feed, SOAP payload or any XML document.

What is the XML Validator?

An XML validator checks whether text is well-formed XML and reports where it breaks.

How the XML Validator works

It parses the XML with the browser's parser; a failure returns the line and reason.

Common mistakes to avoid

  • Confusing well-formed with schema-valid.
  • Unescaped special characters (&, <) inside text.
  • Mismatched or unclosed tags.

Keywords: xml, validate, wellformed.

Runs entirely in your browser - your data is not uploaded.

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the XML Validator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the XML Validator?+

XML Validator uses the standard xml validator formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The XML Validator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the XML Validator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Share-to-grow kit (Reddit, LinkedIn, Medium)
Reddit post
Title: I built/used this free xml validator — instant, no signup

Body: Validate XML well-formedness using the browser DOMParser. Try it: https://freetoolsgalaxy.com/tools/xml-validator
LinkedIn post
XML Validator on Free Tools Galaxy — Validate XML well-formedness using the browser DOMParser. https://freetoolsgalaxy.com/tools/xml-validator
Medium intro
# XML Validator — the free tool I keep coming back to

Validate XML well-formedness using the browser DOMParser.

Try it: https://freetoolsgalaxy.com/tools/xml-validator
Quora answer
The fastest way is to use a free in-browser xml validator: https://freetoolsgalaxy.com/tools/xml-validator. Validate XML well-formedness using the browser DOMParser.

Embed this tool anywhere

Free embed code for blogs, docs and dashboards. Every embed sends a backlink home — helping you and the galaxy grow together.

HTML iframe
Drop into any site — auto-resizes to its content height, theme-aware.
<iframe src="https://freetoolsgalaxy.com/tools/xml-validator?embed=1" title="XML Validator" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
  allow="clipboard-write"></iframe>
<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="ftg-embed-height"){document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source){f.style.height=e.data.height+"px";}});}});</script>
<p><a href="https://freetoolsgalaxy.com/tools/xml-validator" target="_blank" rel="noopener">Powered by XML Validator on Free Tools Galaxy</a></p>
Responsive wrapper
Aspect-locked container — good for blog post bodies.
<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/xml-validator?embed=1" title="XML Validator" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
WordPress / Markdown
Paste in a custom-HTML block or markdown file.
[XML Validator — free online tool](https://freetoolsgalaxy.com/tools/xml-validator)

<iframe src="https://freetoolsgalaxy.com/tools/xml-validator?embed=1" width="100%" height="600" frameborder="0"></iframe>
Text link-back
Minimal credit link — best for sidebars and footers.
<a href="https://freetoolsgalaxy.com/tools/xml-validator" target="_blank" rel="noopener">Try the free XML Validator</a>

Share-to-Grow Kit

Pre-written, ready-to-paste posts for every major channel. Help others discover this tool — and earn backlinks.

Title
I built a free pregnancy due date calculator that works instantly in the browser — no signup, no ads in your face
Body
Hey r/[subreddit],

I kept needing a quick pregnancy due date calculator and most options online were slow or behind paywalls, so I built one that:

• Runs 100% in your browser (your data never leaves your device)
• No signup, no email wall, no popups
• Loads in under a second on mobile

It covers the standard pregnancy due date use cases (pregnancy, due, date, baby) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/pregnancy-due-date-calculator

Happy to take feedback — what's missing?
Post to a relevant subreddit (e.g. r/InternetIsBeautiful, r/webdev, r/productivity). Avoid spammy subs.
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