HTML Encoder/Decoder
Encode special characters to HTML entities or decode HTML entities back to text. Essential for preventing XSS attacks and displaying HTML safely.
About HTML Encoding
HTML encoding converts special characters into HTML entities to prevent them from being interpreted as HTML code. This is crucial for security (XSS prevention), data display, and preserving special characters in web content.
Why HTML Encoding is Essential
🛡️ XSS Prevention
Prevents Cross-Site Scripting attacks by encoding malicious scripts before display
📝 Display HTML Code
Shows HTML tags as text instead of rendering them in browsers
🌐 Special Characters
Preserves copyright symbols, accents, currency signs, and other special characters
📊 Data Integrity
Safely stores and transmits user-generated content with special characters
Common HTML Entities
| Character | Named Entity | Numeric | Description |
|---|---|---|---|
| < | < | < | Less than sign |
| > | > | > | Greater than sign |
| & | & | & | Ampersand |
| " | " | " | Double quote |
| ' | ' | ' | Single quote (apostrophe) |
| © | © | © | Copyright symbol |
| ® | ® | ® | Registered trademark |
| ™ | ™ | ™ | Trademark symbol |
| € | € | € | Euro currency |
| (space) | |   | Non-breaking space |
Named vs Numeric Entities
Named Entities (&name;)
Pros: More readable, easier to remember, shorter
Cons: Limited set, not all characters have names
Numeric Entities (&#num;)
Pros: Universal, works for any Unicode character
Cons: Less readable, longer, harder to edit
Common Use Cases
- ✓XSS Protection: Encode user input before displaying to prevent script injection
- ✓Code Display: Show HTML/XML code snippets in documentation or tutorials
- ✓Blog Comments: Safely display user comments with special characters
- ✓Email Content: Ensure special characters display correctly in HTML emails
- ✓Form Data: Store and transmit form submissions with special characters
- ✓Meta Tags: Properly encode meta descriptions and social media tags
XSS Attack Prevention
Security Critical
Always encode user input before displaying it in HTML to prevent Cross-Site Scripting (XSS) attacks. This is one of the most common web vulnerabilities.
<div>{user_input}</div><div>{htmlEncode(user_input)}</div>When to Use HTML Encoding
✓ Always Encode
- • User-generated content
- • Form submissions
- • URL parameters in HTML
- • Database content display
- • API response data
- • Search results
ℹ️ Sometimes Encode
- • Trusted admin content
- • Pre-sanitized HTML
- • WYSIWYG editor output
- • Template engine output
- • CMS content (with sanitization)
Frequently Asked Questions
What's the difference between HTML encoding and URL encoding?
HTML encoding uses entities like < for display in HTML. URL encoding uses %20 for safe transmission in URLs. They serve different purposes and use different formats. Use HTML encoding for content, URL encoding for URLs.
Should I encode everything in HTML?
No, only encode when displaying untrusted content or special characters. Normal text (A-Z, a-z, 0-9) doesn't need encoding. Always encode user input, special characters (<>&"'), and content from external sources.
Can HTML encoding break my layout?
No, HTML entities render as their original characters. < displays as <, © as ©. The encoding is only visible in source code, not to users. It actually prevents layout breaking from malformed HTML.
Does double-encoding cause problems?
Yes! Encoding already-encoded text turns < into &lt; which displays as "<" instead of "<". Always check if content is already encoded before encoding again.
Is HTML encoding enough for security?
HTML encoding prevents XSS in HTML content, but use appropriate encoding for each context: JavaScript encoding for JS, URL encoding for URLs, CSS encoding for styles. Also use Content Security Policy (CSP) headers for defense in depth.
Do I need to encode in JSON responses?
JSON escaping is different from HTML encoding. For JSON, use JSON.stringify() which handles escaping. Only HTML-encode when inserting JSON content into HTML. Don't HTML-encode JSON API responses.