Complete HTML/XML Formatter Guide: Code Formatting & Validation

What is HTML/XML Formatting?

HTML/XML formatting transforms messy, unreadable markup code into clean, well-structured, and properly indented format. Our formatter supports both HTML and XML with advanced validation, beautification, and optimization features.

Why Our HTML/XML Formatter is Essential:

Clean Code: Transform minified code into readable format
Validation: Detect syntax errors and structural issues
Accessibility: Improve code accessibility compliance
Performance: Optimize code for better loading times
Standards: Ensure compliance with HTML5/XML standards
Team Collaboration: Consistent formatting across projects

HTML Formatting Features

HTML5 Structure Formatting


TestTitle
Content





    
    
    Test


    
        Title
        Content

Semantic HTML Enhancement



    
        Home
        About
    


    Article content




    
        
            Home
            About
        
    


    Article content

Attribute Formatting

Form Formatting






    
        User Login
        
        
            Username:
            
            Enter your registered username
        
        
        
            Password:

XML Formatting Capabilities

XML Structure Beautification


Johnjohn@example.comJanejane@example.com




    
        
            John
            john@example.com
        
        
            Jane
            jane@example.com

Namespace Handling


Content



    
        Content

CDATA and Comments

XML Schema Integration

Code Validation and Error Detection

HTML Validation

Syntax Error Detection




    Test
    
    


    
    
    This should be properly nested
    
    
    
    
    
    
    Modern centered element

Accessibility Validation







Username:

XML Validation

Well-formedness Check

Schema Validation

Beautification and Minification

Beautification Options

Indentation Styles



	
		Tab Indented
	
	
		
			Content
		
	




  
    Space Indented
  
  
    
      Content
    
  




    
        Space Indented
    
    
        
            Content

Attribute Formatting

Minification Features

HTML Minification





    
    Page Title


    
        Main Title
        Some content here.
    




Page TitleMain Title
Some content here.

XML Minification




    
        Product Name
        29.99
    



Product Name29.99

Aggressive Minification Options


Hello World


Hello World
 


Remove comments: Yes/No
Remove optional tags: Yes/No  
Remove quotes from attributes: Yes/No
Remove redundant attributes: Yes/No
Collapse whitespace: Yes/No

Syntax Highlighting

HTML Syntax Highlighting

XML Syntax Highlighting

Syntax Highlighting Features:

Processing instructions: Purple/Magenta ()
Namespaces: Cyan (xmlns:ns, ns:element)
Elements: Blue (element names)
Attributes: Green (attribute names and values)
CDATA sections: Yellow (raw content blocks)
Comments: Gray ()

Customizable Themes

/ Available highlighting themes /
themes: {
  default: "Standard colors",
  dark: "Dark background theme",
  monokai: "Sublime Text style",
  github: "GitHub style",
  vs: "Visual Studio style",
  custom: "User-defined colors"
}

/ Custom theme configuration /
{
  "background": "#ffffff",
  "text": "#000000", 
  "tags": "#0066cc",
  "attributes": "#009900",
  "strings": "#cc0000",
  "comments": "#808080",
  "keywords": "#9900cc"
}

Advanced Formatting Options

Custom Formatting Rules

Element-Specific Rules

// Custom formatting configuration
const formatConfig = {
  indentSize: 4,
  indentType: 'spaces', // or 'tabs'
  maxLineLength: 120,
  
  elements: {
    'script': {
      preserveNewlines: true,
      indentContent: false
    },
    'pre': {
      preserveWhitespace: true,
      skipFormatting: true
    },
    'textarea': {
      preserveContent: true,
      trimWhitespace: false
    }
  },
  
  attributes: {
    sortOrder: ['id', 'class', 'src', 'href', 'type', 'name'],
    breakLongAttributes: true,
    quoteStyle: 'double' // or 'single'
  }
};

Conditional Formatting










    
        Component Title
        
            
            
        
    
    
        Content here

Batch Processing

Multiple File Processing

// Batch format multiple files
const batchFormat = {
  files: ['index.html', 'about.html', 'contact.html'],
  options: {
    indent: 2,
    removeComments: false,
    sortAttributes: true,
    validateHTML: true
  },
  output: {
    overwrite: false,
    suffix: '_formatted',
    directory: './formatted'
  }
};

// Processing results
results = [
  {
    file: 'index.html',
    status: 'success',
    errors: 0,
    warnings: 2,
    optimizations: 'Removed 3 empty lines, sorted 15 attributes'
  },
  {
    file: 'about.html', 
    status: 'warning',
    errors: 0,
    warnings: 1,
    issues: ['Missing alt attribute on img tag line 23']
  }
];

Integration and Export

Export Options

File Format Support

Export Formats:
├── HTML: Standard HTML files (.html, .htm)
├── XHTML: XHTML compliant output (.xhtml)
├── XML: Well-formed XML (.xml)
├── Text: Plain text format (.txt)
├── PDF: Formatted code documentation (.pdf)
└── ZIP: Multiple files archive (.zip)

Integration APIs

// REST API integration
POST /api/format
Content-Type: application/json

{
  "code": "Test",
  "type": "html",
  "options": {
    "indent": 2,
    "validate": true,
    "minify": false
  }
}

Response:
{
  "formatted": "\n\n  \n    Test\n  \n",
  "errors": [],
  "warnings": ["Missing DOCTYPE declaration"],
  "stats": {
    "originalSize": 45,
    "formattedSize": 78,
    "elements": 3,
    "attributes": 0
  }
}

IDE Integration

VS Code Extension

// VS Code settings.json
{
  "htmlxml-formatter.indent": 2,
  "htmlxml-formatter.validate": true,
  "htmlxml-formatter.autoFormat": true,
  "htmlxml-formatter.sortAttributes": true,
  "editor.formatOnSave": true,
  "editor.defaultFormatter": "htmlxml-formatter"
}

Command Line Interface

Install CLI tool
npm install -g htmlxml-formatter-cli

Format single file
htmlxml-format input.html --output formatted.html --indent 4

Format multiple files
htmlxml-format .html --validate --sort-attributes

Watch mode for development
htmlxml-format --watch src/ --output dist/

Best Practices

HTML Best Practices

Semantic Structure

Page Title Article Title September 1, 2023

Accessibility Guidelines



    
        Contact Information
        
        
            Full Name 
            
            
        
        
        
            Email Address *
            
            We'll never share your email

XML Best Practices

Namespace Management




    
        Widget
        29.99
    




    Content

Troubleshooting Guide

Common Issues

HTML Parsing Errors



    Paragraph 1
    
Paragraph 2




    Paragraph 1
    Paragraph 2






Valid nesting

XML Well-formedness Issues



    Content




    Content

Performance Issues

// Large file optimization tips
{
  "streamProcessing": "Enable for files > 1MB",
  "chunkSize": "Process in 100KB chunks", 
  "memoryManagement": "Clear DOM nodes after processing",
  "progressReporting": "Show progress for long operations",
  "webWorkers": "Use background threads for heavy processing"
}

Conclusion

Our HTML/XML Formatter provides comprehensive tools for cleaning, validating, and optimizing markup code. Whether you're working with HTML documents, XML data files, or complex web applications, our formatter ensures clean, valid, and maintainable code.

Key Benefits:

Code Cleaning: Transform messy code into readable format
Validation: Detect and fix syntax errors automatically
Standards Compliance: Ensure HTML5/XML standards adherence
Accessibility: Improve code accessibility compliance
Performance: Optimize code for better loading times

Ready to clean up your markup? Try our HTML/XML Formatter today and experience professional-grade code formatting with advanced validation features!

Last updated: September 2025 | HTML/XML Formatter Guide | DevToolMint Professional Tools

HTML/XML Formatter & Minifier - Complete Guide

📋 Table of Contents

Complete HTML/XML Formatter Guide: Code Formatting & Validation

What is HTML/XML Formatting?

Why Our HTML/XML Formatter is Essential:

HTML Formatting Features

HTML5 Structure Formatting

Title

Title

Semantic HTML Enhancement

Attribute Formatting

Form Formatting

XML Formatting Capabilities

XML Structure Beautification

Namespace Handling

CDATA and Comments

XML Schema Integration

Code Validation and Error Detection

HTML Validation

XML Validation

Beautification and Minification

Beautification Options

Minification Features

Main Title

Main Title

Syntax Highlighting

HTML Syntax Highlighting

Title

XML Syntax Highlighting

Customizable Themes

Advanced Formatting Options

Custom Formatting Rules

Batch Processing

Integration and Export

Export Options

IDE Integration

Install CLI tool

Format single file

Format multiple files

Watch mode for development

Best Practices

HTML Best Practices

XML Best Practices

Troubleshooting Guide

Common Issues

Conclusion

Ready to Try HTML/XML Formatter & Minifier?