HTML Entity Encoder/Decoder

Encode special characters to HTML entities and decode HTML entities back to text. Essential for web development, content management, and data processing.

HTML Entity Encoder/Decoder

Characters: 0
Characters: 0

HTML Entity Reference

Essential Entities

& Ampersand&
< Less than&lt;
> Greater than&gt;
" Quote&quot;
' Apostrophe&#x27;

Common Symbols

© Copyright&copy;
® Registered&reg;
™ Trademark&trade;
€ Euro&euro;
Non-breaking space&nbsp;

Numeric Character References

Decimal: &#8364; → € (Euro symbol)
Hexadecimal: &#x20AC; → € (Euro symbol)
Range: Supports Unicode characters U+0000 to U+10FFFF

What are HTML Entities?

Understanding HTML Entities

HTML entities are special codes that represent characters that have special meaning in HTML or that cannot be directly typed. They start with an ampersand (&) and end with a semicolon (;).

  • • Named Entities: Like &copy; for ©
  • • Numeric Entities: Like &#8364; for €
  • • Hex Entities: Like &#x20AC; for €
  • • Case Sensitive: Entity names must match exactly
  • • Browser Support: Universal support across all browsers

Why Use HTML Entities?

  • • Prevent Rendering Issues: Avoid HTML parsing conflicts
  • • Security: Prevent XSS attacks through proper escaping
  • • Compatibility: Display special characters across all devices
  • • Accessibility: Screen readers can properly interpret entities
  • • Data Integrity: Preserve special characters in data transfer

Common Use Cases

Web Development

  • • Displaying code snippets with HTML tags
  • • Preventing XSS vulnerabilities
  • • Template engine output escaping
  • • Form input validation and sanitization
  • • Email template development
  • • RSS/XML feed generation

Content Management

  • • Blog post content with special characters
  • • CMS data import/export
  • • Multilingual website content
  • • Mathematical and scientific notation
  • • Copyright and trademark symbols
  • • Foreign language characters

Data Processing

  • • CSV file processing with HTML content
  • • Database content migration
  • • API response formatting
  • • Log file analysis and cleanup
  • • Documentation generation
  • • Automated content generation

Essential HTML Entities

Must-Know Entities

& (ampersand)&amp;
< (less than)&lt;
> (greater than)&gt;
" (quotation mark)&quot;
' (apostrophe)&#x27;

Common Symbols

© (copyright)&copy;
® (registered)&reg;
™ (trademark)&trade;
€ (euro)&euro;
£ (pound)&pound;

Practical Examples

Displaying HTML Code

Original Code:
<div class="example">Hello & Welcome!</div>
HTML Entities:
&lt;div class=&quot;example&quot;&gt;Hello &amp; Welcome!&lt;/div&gt;

Mathematical Expressions

Mathematical Text:
E = mc² ∞ π ∑ α β γ ≤ ≥ ≠
HTML Entities:
E = mc&#178; &infin; &pi; &sum; &alpha; &beta; &gamma; &le; &ge; &ne;

Multilingual Content

International Text:
Café naïve résumé piñata Zürich
HTML Entities:
Caf&#233; na&#239;ve r&#233;sum&#233; pi&#241;ata Z&#252;rich

Programming Integration

JavaScript

// Encode HTML entities
function encodeHTML(str) {
  return str
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#x27;');
}

// Decode HTML entities
function decodeHTML(str) {
  const textarea = document.createElement('textarea');
  textarea.innerHTML = str;
  return textarea.value;
}

PHP

// Encode HTML entities
$encoded = htmlspecialchars($text, 
  ENT_QUOTES | ENT_HTML5, 'UTF-8');

// Decode HTML entities
$decoded = html_entity_decode($encoded, 
  ENT_QUOTES | ENT_HTML5, 'UTF-8');

// Encode all applicable characters
$encoded_all = htmlentities($text, 
  ENT_QUOTES | ENT_HTML5, 'UTF-8');

Security Considerations

XSS Prevention

  • • Always encode user input before displaying in HTML
  • • Encode data when generating HTML dynamically
  • • Use context-appropriate encoding methods
  • • Validate and sanitize input on the server side
  • • Implement Content Security Policy (CSP) headers
  • • Regular security audits of encoding practices

Best Practices

  • • Encode output, not input (preserve original data)
  • • Use appropriate encoding for the context (HTML, URL, JS)
  • • Don't double-encode already encoded content
  • • Use established libraries and frameworks
  • • Test encoding with malicious input samples
  • • Document encoding requirements in your codebase

⚠️ Common Vulnerabilities

Dangerous (Unencoded):
<script>alert('XSS')</script>
Safe (Encoded):
&lt;script&gt;alert('XSS')&lt;/script&gt;

Tool Features

Encoding Modes

  • • Basic Mode: Encodes essential HTML characters only
  • • All Mode: Encodes common symbols and special characters
  • • Real-time Processing: Converts as you type
  • • Quick Insert: Common character buttons
  • • Bidirectional: Encode and decode in same interface

Privacy & Performance

  • • Client-side Only: No data sent to servers
  • • Instant Results: Fast local processing
  • • Offline Capable: Works without internet
  • • No Logging: Your data stays private
  • • Cross-platform: Works on all devices