XML Formatter & Validator
Format (pretty print), minify, and validate XML documents instantly - paste your XML, beautify or compress it, and check that it's well-formed, all in your browser.
About the XML Formatter & Validator
XML (Extensible Markup Language) is a markup language widely used for storing and transporting data. This XML formatter helps developers work with XML documents by providing formatting (beautifying/pretty printing), minification, and well-formedness validation in one browser-based tool.
What Is an XML Formatter?
An XML formatter re-indents XML with consistent line breaks and spacing so its element structure is easy to read at a glance. It works by parsing the XML into its actual document structure, then rendering that structure back out with indentation - never by rewriting the text as a string. That's what keeps CDATA sections, comments, attribute values, and mixed text content intact even when they legally contain characters like < or >.
XML Beautifier vs XML Formatter
"XML formatter," "XML beautifier," and "XML pretty printer" all describe the same action: adding indentation and line breaks to make XML readable without changing the underlying data. This tool covers all three under one roof, plus minification (the reverse: stripping that formatting whitespace back out) and validation (checking well-formedness independent of formatting).
Key Features
- ✓Format XML (Beautify/Pretty Print): Add proper indentation (2, 4, or 8 spaces) for readability
- ✓Minify XML: Remove unnecessary formatting whitespace to produce more compact XML
- ✓Validate Well-Formedness: Check for XML syntax errors and tag matching
- ✓Statistics Display: View elements count, attributes, nesting depth, and file size
- ✓Export Options: Copy to clipboard or download as .xml file
- ✓Browser-Based: All processing happens locally for privacy and security
Understanding XML
XML is a flexible, self-descriptive markup language that defines rules for encoding documents in a format that is both human-readable and machine-readable. Unlike HTML which focuses on displaying data, XML is designed to store and transport data.
When to Use Each Mode
Beautify Mode
Use beautify mode when you need to read, understand, or edit XML documents. This mode adds proper indentation and line breaks, making the structure clear and easy to navigate.
Best for: Debugging, configuration file editing, documentation, code reviews
Minify Mode
Use minify mode to reduce file size for data transmission or storage. This removes all unnecessary whitespace while preserving the XML structure and data.
Best for: Web services, API responses, reducing bandwidth, storage optimization
Validate Mode
Use validate mode to check if your XML is well-formed. This identifies syntax errors like unclosed tags, invalid characters, or improper nesting.
Best for: Syntax checking, pre-deployment validation, error debugging, quality assurance
XML Well-Formedness Rules
- XML Declaration: Optional but recommended:
<?xml version="1.0"?> - Single Root Element: Every XML document must have exactly one root element
- Proper Nesting: All tags must be properly nested and closed in the correct order
- Case Sensitive: XML tags are case-sensitive (<Book> ≠ <book>)
- Attribute Quotes: All attribute values must be enclosed in quotes
- Special Characters: Use entities for special characters (< > & " ')
- Self-Closing Tags: Empty elements can use self-closing syntax: <tag/>
Common XML Errors
- Unclosed Tags: Every opening tag must have a matching closing tag
- Improper Nesting: Tags must be closed in the reverse order they were opened
- Missing Quotes: Attribute values must be in single or double quotes
- Invalid Characters: Special characters must be escaped using entities
- Multiple Root Elements: Only one root element is allowed per document
- Case Mismatch: Opening and closing tags must have identical case
Use Cases
Configuration Files
Format and validate XML configuration files for applications and web services
SOAP Web Services
Debug and format SOAP request/response messages for API testing
RSS/Atom Feeds
Create and validate RSS or Atom feed XML for content syndication
Data Exchange
Format XML data for import/export between different systems
XML vs JSON
| Feature | XML | JSON |
|---|---|---|
| Data Format | Markup language | Data notation |
| Verbosity | More verbose | More concise |
| Attributes | Supports attributes | No attributes |
| Namespaces | Built-in support | No namespace support |
| Comments | Supported | Not supported |
Frequently Asked Questions
What is an XML formatter?
An XML formatter takes XML and re-indents it with consistent line breaks and spacing so the element hierarchy is easy to read, without changing the underlying data. This tool formats (also called "beautifying" or "pretty printing") XML entirely in your browser.
How do I format XML online?
Paste your XML into the input box, choose an indent size (2, 4, or 8 spaces), and click Beautify XML. The formatted result appears in the output box, ready to copy or download as a .xml file.
What's the difference between formatting and validating XML?
Formatting changes only whitespace and indentation for readability. Validating checks whether the XML is well-formed - correct tag nesting, closed tags, quoted attributes - independent of how it's indented. This tool does both, plus minification to strip formatting whitespace back out.
What does "pretty print" mean for XML?
Pretty printing is another name for formatting or beautifying: adding indentation and line breaks to XML so its structure is visually clear. It has no effect on the data itself, only on how the markup is laid out.
Does formatting or minifying XML change the data?
No. The tool parses your XML into its actual document structure - not as plain text - and only adjusts whitespace at points where it's safe to do so, between structural elements. Text content, CDATA sections, comments, processing instructions, and attribute values are preserved exactly as written. If the XML isn't well-formed to begin with, no formatted or minified output is produced at all.
Can this tool detect malformed XML?
Yes. Every mode - beautify, minify, and validate - parses your input with the same well-formedness check first. Unclosed tags, mismatched nesting, and other structural errors are reported with a description of the problem, and no formatted output is generated for invalid input.
Does this XML formatter support namespaces, CDATA, and comments?
Yes. Default and prefixed XML namespaces, CDATA sections, comments, processing instructions, DOCTYPE declarations, and entities are all preserved correctly, since the tool works from the parsed document structure rather than treating XML as a string of text to search and replace.
Can this tool validate against a DTD or XSD schema?
No. It checks well-formedness - correct syntax and tag structure - which is different from schema validation against a DTD or XML Schema (XSD), which checks that specific elements, attributes, and data types match a defined schema. This tool doesn't perform DTD/XSD validation.
Is my XML uploaded to a server?
No. Formatting, minifying, and validation all run in your browser using its built-in XML parser. Your XML is never sent to ProURLMonitor servers.
Curious how XML parsing works under the hood - the difference between DOM and SAX parsing, and how parsing relates to formatting and validation? See What Is an XML Parser and How Does XML Parsing Work?
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