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XML Formatter

Format and validate XML documents

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Last Updated: March 2, 2026
avatarBy Viblaa Team

Syntax validation

Format and minify

Error highlighting

Copy formatted XML

The SOAP response arrives as a single line of XML. 47,000 characters without a single line break. Somewhere in there is the error message explaining why the payment failed. Good luck finding it.

XML may be machine-readable, but humans need to debug it too. This formatter transforms any XML—no matter how compressed or malformed—into properly indented, readable documents with syntax validation.

What is XML Formatting?

XML formatting adds proper indentation and line breaks to XML documents, making nested structures visible and readable. A good formatter also validates syntax, catching issues like mismatched tags or invalid characters before they cause problems.

Before and after:

<!-- Before -->
<order><customer><name>John</name><email>john@example.com</email></customer><items><item><sku>ABC123</sku><qty>2</qty></item></items></order>

<!-- After -->
<order>
    <customer>
        <name>John</name>
        <email>john@example.com</email>
    </customer>
    <items>
        <item>
            <sku>ABC123</sku>
            <qty>2</qty>
        </item>
    </items>
</order>
Formatting Reveals Structure

XML's power is in its hierarchy. Proper formatting makes parent-child relationships visible at a glance, something impossible in compressed single-line format.

Why People Actually Need This Tool

XML Remains Everywhere

Despite JSON's rise, XML powers SOAP APIs, RSS feeds, SVG graphics, Office documents, Android manifests, and countless enterprise systems. You'll encounter it.

  1. API debugging — Read SOAP responses and XML payloads clearly.

  2. Configuration editing — Format web.config, pom.xml, and other config files.

  3. Data inspection — Examine XML exports from databases and applications.

  4. SVG editing — Make SVG graphics readable for manual editing.

  5. Feed debugging — Troubleshoot RSS and Atom feeds.

  6. Documentation — Format XML examples for technical docs.

  7. Validation — Catch syntax errors before they break systems.

How to Use the XML Formatter

  1. Paste your XML — Any XML document, regardless of current formatting.

  2. Format instantly — Get properly indented output with syntax validation.

  3. Review any errors — See validation messages for malformed XML.

  4. Copy formatted XML — Use in your editor or documentation.

XML FeatureFormatting BehaviorPurpose
Nested elementsEach on new line, indentedShow hierarchy
AttributesKept on same line as opening tagKeep tags compact
Text contentInline with containing elementPreserve text nodes
Empty elementsSelf-closing <tag />Reduce verbosity
CommentsPreserved, properly indentedMaintain documentation
Whitespace Can Be Significant

In some XML contexts (like mixed content), whitespace matters. Formatting adds whitespace that might affect certain parsers. Test formatted output with your actual system.

Real-World Use Cases

1. The SOAP API Debug

Context: Enterprise integration with SOAP web service failing intermittently.

Problem: Error responses are single-line XML impossible to read in logs.

Solution: Format the XML to see error code nested 5 levels deep in the fault structure.

Outcome: Actual error identified: authentication token expired. Would have taken hours to find unformatted.

2. The Maven Configuration

Context: Java project with complex pom.xml causing build failures.

Problem: Pom file is 800 lines, previously formatted inconsistently by different IDEs.

Solution: Reformat entire file with consistent indentation.

Outcome: Duplicate dependency discovered that was hidden by bad formatting.

3. The SVG Optimization

Context: Designer exported SVG has unnecessary groups and transforms.

Problem: SVG exported as single line, impossible to identify what to remove.

Solution: Format SVG to see structure. Manually remove unnecessary wrapper groups.

Outcome: SVG file size reduced 40%, loads faster, easier to animate.

4. The RSS Feed Troubleshooting

Context: Podcast RSS feed rejected by Apple Podcasts.

Problem: Error says "invalid XML" but feed looks correct.

Solution: Format reveals unclosed tag buried in episode description.

Outcome: Fix the tag, feed validates, podcast published.

5. The Android Manifest Review

Context: Android app requesting too many permissions.

Problem: AndroidManifest.xml permissions scattered, hard to audit.

Solution: Format manifest, group and comment permission sections.

Outcome: Three unnecessary permissions identified and removed.

6. The Office Document Extraction

Context: Need to extract data from Excel files programmatically.

Problem: XLSX internals are compressed XML, exported as single line.

Solution: Format the extracted XML to understand structure.

Outcome: Build parser targeting correct paths for required data.

7. The Config Migration

Context: Migrating from XML config to YAML, need to understand current structure.

Problem: Legacy XML config is poorly formatted, hard to understand hierarchy.

Solution: Format XML to clearly see all settings and their nesting.

Outcome: Accurate migration with no missed settings.

Common Mistakes and How to Avoid Them

XML Has Strict Rules

Unlike HTML, XML requires properly closed tags, case-sensitive names, and quoted attributes. Formatters help catch these issues.

Assuming Formatted XML Is Valid XML
❌ The Mistake
Formatting makes invalid XML readable but doesn't fix underlying errors.
âś… The Fix
Use validation in addition to formatting. Fix errors before relying on the output.
Adding Whitespace to CDATA Sections
❌ The Mistake
Formatting that adds whitespace inside CDATA, potentially breaking content.
âś… The Fix
Good formatters preserve CDATA content exactly. Verify your formatter handles CDATA correctly.
Ignoring Encoding Declarations
❌ The Mistake
Copying formatted output without preserving the XML declaration with encoding specification.
âś… The Fix
Always include the XML declaration with correct encoding when saving formatted output.
Formatting Minified XML for Production
❌ The Mistake
Using formatted (larger) XML in production where file size matters.
âś… The Fix
Format for human work. Minify for production. Different tools for different purposes.
Breaking Namespace Prefixes
❌ The Mistake
Manually editing formatted XML and accidentally removing namespace declarations.
âś… The Fix
Be careful with xmlns declarations. They affect all descendant elements using that prefix.

Privacy and Data Handling

This XML Formatter operates entirely in your browser.

  • No XML is sent to any server.
  • No documents are logged or stored.
  • No account required.
  • Works completely offline.

Format sensitive SOAP responses and configuration files safely—nothing leaves your device.

Conclusion

XML's verbosity is a feature—it's self-documenting and unambiguous. But that verbosity becomes a bug when you're staring at a 50KB single-line response trying to find an error.

This formatter makes XML readable again. Paste any XML—compressed API responses, tangled config files, minified SVGs—and get properly structured output you can actually work with.

Machines can read anything. Sometimes humans need a little help.

Frequently Asked Questions