XML Formatter: Beautify, Minify & Validate XML Online

A free online XML formatter for beautifying, minifying, and validating XML in one place. Paste your code to apply clean indentation, create compact output, or check for structural errors in your browser.

Free with no sign-up required: Use the formatter in your browser without creating an account.
Format with consistent indentation: Rewrites XML using nesting-depth-based indentation and line breaks for readability.
Minify to reduce file size: Strips whitespace between tags to create compact, single-line output for production deployments.
Built-in XML validator: Checks well-formedness — unclosed tags, mismatched pairs, and missing declarations — with line-numbered error reports.
CodeMirror editors: Input and output editors show XML syntax highlighting and line numbers.
Browser-based processing: Formatting, minifying, and validation run in browser-side JavaScript.

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Output Result

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Processed Size

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Compression Rate

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Format & Minify — Sample Results

Operation	Input Size	Output Size	Compression	Lines (Before → After)
Format (compact → readable)	1.2 KB	1.8 KB	−50.0% (increase)	1 → 45
Minify (readable → compact)	1.8 KB	1.1 KB	+38.9%	45 → 1
Format (API response)	4.5 KB	6.2 KB	−37.8% (increase)	3 → 120
Minify (sitemap.xml)	12.0 KB	8.1 KB	+32.5%	350 → 1
Validate (error detection)	2.3 KB	—	—	Errors: 3 (line 12, 34, 67)

How to Use the XML Formatter

Paste or type your XML: Enter your XML code into the input editor. A sample XML document is pre-loaded; replace it with your own content when you are ready.
Format, beautify, or minify: Click Format to apply consistent indentation and line breaks that reflect element nesting depth. Click Minify to strip all whitespace and produce a compact single-line document for production use.
Check for errors: Click Validate at any time to check for syntax errors. Each detected problem is listed with its line number and a clear explanation.
Save your result: Click Download to save the processed XML as an .xml file, or click Copy Result to place it on your clipboard.

Practical Applications

Well-formed vs. valid XML: This tool checks for well-formedness — matching tags, proper nesting, and valid syntax. It does not validate against external schemas (DTD/XSD). A well-formed document is syntactically correct; a valid document also conforms to a specific schema.

Batch processing: To format or minify multiple XML files at once, use the XML Batch Formatter for multi-file processing.

Use the stats panel: The statistics cards below the editors show original vs. processed size, line counts, and compression rate — useful for measuring file size reduction after minification.

Browser-side processing: XML formatting, minifying, and validation run in your browser via JavaScript.

FAQ

Q. How do I format XML online?

Paste your XML into the input editor and click Format. The tool rewrites the markup using consistent 4-space indentation and line breaks that reflect the nesting depth of each element. Tag names, attributes, and text content are preserved without changes.

Q. What does the XML validator check?

The validator checks your document for well-formedness — unclosed tags, mismatched opening and closing pairs, missing or malformed XML declarations, duplicate attributes, and improper nesting. Each detected issue is reported with its line number and a brief explanation so you can locate and fix errors.

Q. How do I minify XML to reduce file size?

Click Minify to strip all whitespace between tags, producing a compact single-line document. Text content inside elements is preserved. The stats panel displays the compression rate so you can see the size reduction — typically 30–40% for common configuration files and data feeds.

Q. What is the difference between well-formed and valid XML?

A well-formed document follows basic XML syntax rules: every opening tag has a matching closing tag, attributes are quoted, elements are properly nested, and there is exactly one root element. A valid document additionally conforms to a defined schema such as a DTD or XSD. This tool checks for well-formedness; schema validation is not included.

Q. Is my XML data sent to a server?

No. Formatting, minifying, and validation are performed by JavaScript running in your browser. The XML you paste into the editor is processed on the page rather than sent to a server.

About the XML Formatter

This free online XML formatter lets you beautify, minify, and validate XML directly in your browser. Paste your code to debug a minified API response, standardize a configuration file for code review, or create a compact sitemap.xml file.

Both the input and output editors are powered by CodeMirror, with syntax highlighting, line numbers, and bracket matching. A built-in validator checks your document for well-formedness and reports unclosed tags, mismatched pairs, and missing declarations with line-numbered errors. Formatting, minifying, and validation run in your browser via JavaScript.

Use it for XML configuration files, sitemap.xml payloads, data feeds, and XML structure lessons when you need readable formatting, compact output, or well-formedness checks without installing desktop software.

Common Use Cases

Debugging XML API responses: REST APIs, SOAP services, and RSS feeds often return minified or poorly formatted XML. Paste the response into the input editor, click Format, and view the hierarchy with indentation and line numbers.
Code review and team collaboration: Standardize XML formatting before committing configuration files, data exports, or document templates to version control. Consistent indentation makes diffs and pull request reviews easier.
Production optimization: Minify XML sitemaps, configuration files, and data feeds before deployment. Smaller XML output can reduce transfer size, especially for large sitemap.xml files.
Error diagnosis before deployment: Validate XML documents before they reach production environments. The validator catches syntax errors — unclosed tags, duplicate attributes, improper nesting — and lists each issue with its line number, so you can fix problems before they cause parser failures.
Learning and teaching XML: Students and educators can use the formatter to visualize XML hierarchy and the validator to get direct feedback on well-formedness. Alternating between Format and Minify demonstrates the relationship between readability and compactness in XML markup.

XML Structure Quick Reference

Concept	Description	Example
XML Declaration	Optional first line specifying version and encoding	`<?xml version="1.0" encoding="UTF-8"?>`
Root Element	Exactly one element that contains all others	`<catalog>...</catalog>`
Child Elements	Nested elements inside the root or other elements	`<book><title>...</title></book>`
Attributes	Name-value pairs inside opening tags	`<book category="web">`
Self-closing Tags	Elements without content, closed with `/>`	`<break fast="true"/>`
Comments	Ignored by parsers, used for documentation	`<!-- Note: -->`
CDATA Sections	Blocks of text not parsed as XML markup	`<![CDATA[<raw>text</raw>]]>`

Tips for Working with XML

Always validate before deploying: Run your XML through the validator before pushing configuration files, sitemaps, or data feeds to production. A single unclosed tag can cause the entire document to fail parsing.
Use minification for production, formatting for development: Minified XML is compact but difficult for humans to read. Keep a formatted version in your source repository and minify only during the build or deploy step.
Check encoding declarations: If your XML contains special characters (accented letters, symbols, non-Latin scripts), ensure the encoding declaration matches your file's actual encoding — typically UTF-8. Mismatched encoding is a common source of parsing errors.
Watch for duplicate attributes: XML does not allow two attributes with the same name on a single element. The validator catches this, but it is easy to overlook when hand-editing large documents.
Use CDATA for embedded content: When embedding HTML, JavaScript, or other markup inside an XML element, wrap it in a CDATA section to prevent the parser from treating angle brackets as XML tags.