HTML Encoder/Decoder
Convert special characters to HTML entities and decode them back to plain text. Essential for preventing XSS attacks, displaying code snippets, and ensuring proper character rendering in HTML. All processing happens in your browser for complete privacy.
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About HTML Encoding
HTML encoding converts special characters into HTML entities to display them correctly in web pages and prevent XSS vulnerabilities.
- Named entities: Use readable names like < > & instead of numeric codes
- Encode all: Convert every character to entities, including letters and numbers
- Line by line: Process each line independently, useful for multiple entries
- Live mode: See results in real-time as you type (all processing happens in your browser)
Common entities: < (<), > (>), & (&), " ("), (non-breaking space)
What is HTML Encoding?
HTML encoding, also known as HTML entity encoding or HTML escaping, is the process of converting special characters into their corresponding HTML entity representations. This ensures that these characters are displayed as text rather than being interpreted as HTML markup or code by web browsers.
For example, the less-than symbol < is encoded as < to prevent browsers from treating it as the beginning of an HTML tag. Similarly, the ampersand & becomes & to avoid confusion with entity references.
HTML entities come in two forms: named entities (like © for ©) and numeric entities (like © or © for ©). Named entities are more readable, while numeric entities can represent any Unicode character.
This encoding process is crucial for web security, preventing XSS (Cross-Site Scripting) attacks, displaying code examples, and ensuring proper rendering of special characters across different browsers and platforms.
Common Use Cases for HTML Encoding
XSS Attack Prevention
Encoding user-generated content prevents malicious scripts from being executed. When users input text containing HTML or JavaScript, encoding ensures it displays as plain text rather than executable code, protecting your website and users from XSS vulnerabilities.
Displaying Code Snippets
When showing HTML, XML, or other markup code examples on your website, encoding prevents the browser from interpreting tags. This allows you to display code exactly as written, making it perfect for tutorials, documentation, and code-sharing platforms.
Special Character Display
Display copyright symbols (©), trademarks (™), currency symbols (€, £, ¥), mathematical operators (×, ÷), and other special characters that might not render correctly in all browsers or encodings. HTML entities ensure consistent display across platforms.
Form Data Processing
When processing form submissions, encoding special characters prevents issues with database storage, ensures data integrity, and protects against SQL injection when combined with proper parameterized queries. It's essential for safely handling user input.
Email Content
HTML emails require proper encoding of special characters to display correctly across different email clients. Encoding ensures your message appears as intended, whether viewed in Gmail, Outlook, or mobile email apps, preventing formatting issues.
XML and RSS Feeds
XML documents and RSS feeds have strict syntax rules. Encoding special characters like <, >, and & is mandatory to create valid XML. This ensures your feeds parse correctly in RSS readers and XML processors without syntax errors.
Essential HTML Entities Reference
| Character | Named Entity | Numeric Code | Description |
|---|---|---|---|
| < | < | < | Less than sign |
| > | > | > | Greater than sign |
| & | & | & | Ampersand |
| " | " | " | Double quotation mark |
| ' | ' or ' | ' | Single quotation mark (apostrophe) |
| |   | Non-breaking space | |
| © | © | © | Copyright symbol |
| ® | ® | ® | Registered trademark |
| ™ | ™ | ™ | Trademark symbol |
| € | € | € | Euro currency symbol |
| £ | £ | £ | Pound sterling symbol |
| ¥ | ¥ | ¥ | Yen/Yuan currency symbol |
These are the most commonly used HTML entities. Our tool supports hundreds more including Greek letters, mathematical symbols, arrows, and special punctuation marks.
Advanced Features
Named Entities vs. Numeric Codes
Choose between human-readable named entities (like ©) or universal numeric codes (like ©).
- Named entities: More readable and memorable, but limited to predefined character sets. Ideal for common symbols like copyright, trademark, and currency symbols.
- Numeric codes: Can represent any Unicode character using decimal (
&#N;) or hexadecimal (&#xN;) notation. Perfect for emoji, rare symbols, and international characters.
Encode All Characters
Enable this option to convert every character, including regular letters and numbers, into numeric HTML entities. This creates heavily obfuscated text useful for:
- Email address protection from spam bots
- Hiding text from simple scrapers while keeping it visible to users
- Creating puzzles or encoded messages
- Testing HTML entity decoder implementations
Note: This significantly increases text size and may impact page load times with large amounts of content.
Line-by-Line Processing
Process multiple independent text entries simultaneously, with each line encoded or decoded separately. Perfect for:
- Batch processing lists of HTML snippets
- Converting multiple strings in database migrations
- Encoding form field values in bulk
- Processing CSV or TSV data containing HTML
Live Mode
Enable live mode for instant encoding or decoding as you type. All processing happens directly in your browser using JavaScript with no data sent to any server. Perfect for learning how different characters are encoded, testing quick conversions, or understanding HTML entity representations in real-time.
Frequently Asked Questions
What's the difference between HTML encoding and URL encoding?
HTML encoding converts special characters to HTML entities (like <) for display in HTML documents, while URL encoding uses percent-encoding (like %3C) for transmitting data in URLs. HTML encoding is for content display and XSS prevention, while URL encoding is for safe transmission of data in web addresses and query parameters. They're complementary but serve different purposes.
Does HTML encoding prevent all XSS attacks?
HTML encoding is essential for XSS prevention but not sufficient on its own. It prevents attacks when user input is displayed in HTML content, but additional measures are needed for data in JavaScript contexts, CSS, or HTML attributes. Use context-aware encoding, Content Security Policy (CSP), input validation, and frameworks with built-in XSS protection for comprehensive security. Always follow OWASP guidelines for web application security.
Do I need to encode all special characters?
At minimum, always encode <, >, &, ", and ' in user-generated content to prevent XSS. For UTF-8 encoded pages, you don't need to encode international characters (like accented letters or Chinese characters), but you may choose to for compatibility with older systems or email clients. Encoding non-breaking spaces and special symbols depends on your specific use case and target audience.
Can I decode doubly-encoded HTML entities?
Yes, but you'll need to decode multiple times. Sometimes data gets encoded twice (like &lt; instead of <). Our decoder handles one level of encoding per operation, so run the decoder twice to fully decode double-encoded text. You can use the swap button to quickly move output to input for sequential decoding operations.
Why use named entities instead of Unicode characters directly?
While modern UTF-8 encoding supports Unicode characters directly, HTML entities offer several advantages: guaranteed compatibility with older browsers and email clients, protection against encoding corruption during data transmission, explicit indication of special characters in source code, and prevention of issues with systems that don't properly handle Unicode. For critical symbols (©, ®, ™) and HTML-significant characters (<, >, &), entities are the safer choice.
Is my data safe when using this tool?
Absolutely. All encoding and decoding operations happen entirely in your browser using JavaScript. No data is ever sent to our servers or any third party. You can verify this by disconnecting from the internet after loading the page—the tool will continue to work perfectly. Your privacy and data security are completely protected. You can even use this tool offline once the page is loaded.
What's the difference between ' and '?
Both represent the apostrophe/single quote character. ' is the numeric entity and works universally in all HTML versions. ' is the named entity but isn't defined in HTML4, only in XHTML and HTML5. For maximum compatibility, use ' or simply encode as needed. Modern browsers support both, but ' is safer for legacy support.
How do I encode emoji or other Unicode symbols?
Emoji and most Unicode symbols don't have named entities, so they're encoded using numeric entities. For example, 😀 becomes 😀 or 😀 (hex). However, modern web pages with UTF-8 encoding can display emoji directly without encoding. Use HTML entity encoding for emoji only if you need compatibility with older systems or want to prevent encoding issues during data transmission.
Can I use this tool for email address obfuscation?
Yes, using the "Encode All" option converts every character to numeric entities, which can help hide email addresses from simple spam bots. However, sophisticated scrapers can decode HTML entities, so this provides only basic protection. For better protection, combine entity encoding with JavaScript-based rendering, contact forms instead of direct mailto: links, or CAPTCHA verification. Entity encoding adds a layer of obfuscation but shouldn't be your only anti-spam measure.
What browsers support this tool?
This tool works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. It requires JavaScript to be enabled and uses standard DOM APIs for text manipulation. The tool is fully responsive and works on desktop computers, tablets, and mobile devices. For best experience, use the latest version of your preferred browser. Internet Explorer is not supported due to missing modern JavaScript features.
Best Practices for HTML Encoding
1. Always Encode User Input
Never trust user-generated content. Always encode special characters before displaying user input in HTML pages to prevent XSS attacks. This includes form submissions, comments, URL parameters, and any external data sources.
2. Use Context-Appropriate Encoding
Different contexts require different encoding: HTML content needs HTML entity encoding, JavaScript strings need JavaScript escaping, CSS values need CSS escaping, and URLs need percent-encoding. Use the right encoding method for each context.
3. Set Proper Character Encoding
Always declare UTF-8 encoding in your HTML documents using <meta charset="utf-8">. This ensures consistent character rendering and reduces the need for excessive entity encoding of international characters.
4. Don't Double-Encode
Avoid encoding already-encoded data, which creates double-encoded entities that display incorrectly (like showing < instead of <). Check if data is already encoded before applying additional encoding.
5. Use Libraries and Frameworks
Modern frameworks like React, Vue, and Angular automatically encode output by default. Leverage these built-in protections rather than manually encoding everywhere. Only use manual encoding when necessary (like generating HTML strings or working with legacy code).
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