What does "well-formed" mean for XML?

It means every tag is properly opened and closed, correctly nested, and the document has exactly one root element — the basic structural rules of XML.

Does this validate against a schema (XSD/DTD)?

No — this checks only that the XML is well-formed, not that it conforms to a specific schema.

Is my XML data uploaded anywhere?

No — validation uses your browser's native XML parser and never sends data to a server.

What is a common cause of malformed XML?

Unclosed tags, mismatched tag names, or more than one root element are the most frequent causes.

Does this work on very large XML documents?

Yes, limited only by your browser's available memory.

Can I validate an XML fragment without a root element?

No — a valid XML document requires a single root element; wrap a fragment in one temporary root tag to validate it.

Outils JSON & Code

Validateur XML — Outil en Ligne Gratuit

Vérifiez si un bloc XML est bien formé.

Utiliser Cet Outil

Fonctionne dans Votre Navigateur
Résultats Instantanés
100% Privé

Your Text

Your result will appear here.

What Is an XML Validator?

An XML validator checks whether a document is well-formed — every tag properly opened and closed, correctly nested, with a single root element — and reports the parser's exact error message if it isn't.

This is distinct from schema validation (checking against an XSD or DTD): this tool confirms the XML is structurally valid on its own terms, which is the first thing worth checking before anything else.

Qui Utilise Cet Outil ?

Pour les Entreprises

Confirm an XML API response or feed is well-formed before processing it.

Pour un Usage Personnel

Check a hand-edited XML file for a mismatched tag.

Pour les Étudiants

Learn what makes XML well-formed for a course assignment.

Pour les Bureaux

Validate an XML export before importing it into another system.

Pourquoi Utiliser Cet Outil

Fonctionnalités Clés

Clear Pass/Fail Result

Instantly see whether your XML is well-formed.

Parser Error Detail

See the exact parser error message when something is wrong.

Instant Validation

Results update immediately as you paste or edit.

100% Private

Your data is never uploaded — validation happens entirely in your browser.

Le Résultat

Avantages

Pinpoint Errors Fast

Get a specific parser error instead of guessing what's wrong.

Quick Sanity Check

Confirm well-formed XML before passing it to another system.

Nothing Uploaded

Safe for sensitive data, since nothing leaves your browser.

Étape par Étape

Comment Utiliser Validateur XML

Paste Your XML

Add the XML you want to check.

Read the Result

See instantly whether it's well-formed, with the parser error if not.

Fix and Re-Check

Correct any reported issue and check again.

Spécifications

Détails Techniques

Détail	Valeur
Entrée	Any text, checked against XML well-formedness rules
Traitement	No practical limit — handled entirely by your browser
Sortie	Uses the browser's native XML parser (DOMParser) for accurate checks

Vous Pouvez le Vérifier

Confidentialité & Sécurité

Ce qui se passe réellement avec votre fichier lorsque vous utilisez cet outil.

100% Client-Side

This tool runs entirely inside your browser using JavaScript — nothing you type or generate is ever sent anywhere.

No Upload, Ever

There is no file upload and no server processing step — your data never leaves your device.

Works Offline

Once this page has loaded, the tool keeps working even without an internet connection.

Nothing Stored

Nothing you enter is saved on our servers — refreshing the page clears everything.

No Tracking of Your Input

We have no way to see what you type, generate or convert with this tool.

Obtenir de Meilleurs Résultats

Astuces

Check for Unclosed Tags First

A single unclosed tag is one of the most common causes of malformed XML.

Remember XML Needs One Root Element

Unlike HTML, XML requires exactly one top-level root element wrapping everything else.

Questions Fréquentes