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The HTML Entity Encode/Decode tool converts special characters in text to their HTML entity equivalents and vice versa. This is essential for safely displaying user-generated content in HTML documents and preventing XSS vulnerabilities.

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Use Cases

  • Sanitizing user input before displaying it in HTML pages
  • Encoding special characters like <, >, &, ", and ' for safe HTML rendering
  • Decoding HTML entities from scraped web content or API responses
  • Preparing text for XML/HTML attributes where special characters must be escaped
  • Debugging HTML source code by decoding entity-encoded content

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How It Works

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Encode Mode (Default)

Converts these special characters to HTML entities:
  • & → &amp;
  • < → &lt;
  • > → &gt;
  • " → &quot;
  • ' → &#39;

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Decode Mode

Converts HTML entities back to their original characters in reverse order.
The decoder handles the five most common HTML entities. For comprehensive entity support including named entities like &nbsp;, &copy;, etc., use a dedicated HTML parser.

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Input Format

Encode: Plain text with special characters 
Click the <button> to "Save & Continue"
Decode: HTML entity-encoded text 
Click the &lt;button&gt; to &quot;Save &amp; Continue&quot;

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Output Format

Encode Output: 
Click the &lt;button&gt; to &quot;Save &amp; Continue&quot;
Decode Output: 
Click the <button> to "Save & Continue"

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Examples

Input:
<script>alert('XSS')</script>

Output:
&lt;script&gt;alert(&#39;XSS&#39;)&lt;/script&gt;

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Technical Details

Located in lib/tools/engine.ts:466-467
The tool uses a synchronous string replacement pipeline:
  • Encode: Replaces special characters in a specific order (& first, then < > ” ’)
  • Decode: Reverses the process in the correct order (& last to avoid double-decoding)

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Performance

  • Synchronous processing: All operations run client-side with no network calls
  • No regex overhead: Uses simple string replacements for maximum speed
  • Memory efficient: Works with strings up to 5MB
This tool is designed for basic HTML entity encoding/decoding. For complex scenarios involving the full spectrum of named HTML entities (600+ entities like &mdash;, &trade;, etc.), use a dedicated HTML parser library.

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